Defensive integration through cooperative re-bordering? How member states use internal border controls in Schengen

ABSTRACT Following the refugee crisis in 2015 and the coronavirus pandemic in 2020, the use of internal border controls within the EU expanded considerably. This change seems to be at odds with the freedom of movement within the Schengen Area, a cornerstone of European integration. Previous research has been inconclusive as to whether this re-bordering signals a move towards renationalisation and disintegration or if it should be understood as a reconfiguration of European cooperation. This article takes a long-term perspective on the use of internal border controls and compares, through content analysis, the prevalence of renationalisation and European integration themes in member states’ notifications of internal border controls from 2006 to 2020. While controls have become more extensive in duration and scope over time, the results show that, contrary to expectations, increased focus on national security was not accompanied by less commitment to European integration in these notifications. Thus, rather than a sign of disintegration, it is argued that internal border controls can be understood as a reconfiguration of the European border regime towards cooperative but defensive integration.


Introduction
The removal of obstacles to free movement in the Schengen area is at the core of European integration.Freedom of movement is the most appreciated European Union (EU) policy among its citizens, and public support for free movement in the Schengen area has remained strong despite being challenged by recent crises (Lutz & Karstens, 2021).In the autumn of 2015, as a reaction to the crisis of migration management, a number of member states introduced temporary internal border controls (IBCs) at their national borders.Before this crisis, the option of introducing IBCs had been used very sparingly by the member states.The 2015 situation is therefore often characterized as a 'crisis of the Schengen regime' (Schimmelfennig, 2018) or simply as the 'Schengen crisis' (Börzel & Risse, 2018), in which the principle of free movement was challenged.That the policy responses of member states in crisis turned towards national re-bordering raised the question of whether we are witnessing European disintegration (e.g.Biermann et al., 2019;Börzel & Risse, 2018;Scipioni, 2018;Taggart & Szczerbiak, 2018).In March 2020, the outbreak of the coronavirus pandemic resulted in further use of temporary internal border controls, which further limited freedom of movement in the Schengen area.
How should the use of internal border controls be understood?The extent to which these controls challenge European integration is contested.Some argue that this crisis of Schengen signaled a shift towards renationalisation, which can undermine the area of free movement and potentially lead to disintegration (Brekke & Staver, 2018;Eilstrup-Sangiovanni, 2021).On the other hand, it has also been argued that rather than signaling its demise, the use of IBCs is an inherent part of Schengen (Votoupalová, 2019).Others have pointed out that combined with extensive re-bordering at the external borders, internal re-bordering is indicative of 'defensive integration' rather than disintegration (Schimmelfennig, 2021).
The contributions of this article are both theoretical and empirical.While there are some in-depth studies of justifications and narratives around the use of internal border controls, these studies have often focused on a specific time period, for example related to the refugee crisis (e.g.Karamanidou & Kasparek, 2022;Kriesi et al., 2021) or the coronavirus pandemic (Martín, 2020;Wolff et al., 2020).In contrast, studies that cover a longer time-period have illustrated the expansion of IBCs during crises (Heinikoski, 2020) and shown how IBCs have lost their temporary nature to become a 'new normal' (Gülzau, 2021), but not covered how member states' justify their actions more in-depth.Contributing empirically to the overarching questions of how the use of IBCs has developed over time, and whether the expansion of internal controls also indicates a loss of commitment to the principle of freedom of movement among the member states, the present article therefore combines comparison over time with close-reading of these justifications.The analysis is based on an original dataset consisting of memberstates' notifications of the introduction or prolongation of IBCs between 2006 and 2020, in total 262 such notifications.In order to compare 'normal' use to use in crisis, the analysis compares the development of internal border controls over four periods: the pre-crisis 2006-2015, the 'refugee crisis ' of 2015, the in-between period 2016-2020, and finally the coronavirus crisis from March to December of 2020.
The theoretical underpinnings of this article connect to the literature on integration and re-bordering in the EU.The article contributes to the ongoing debate on whether internal re-bordering through the increased use of internal border controls should be understood as a sign of European disintegration or not.Elaborating on Schimmelfennig's concept of 'defensive integration', the present article argues that internal re-bordering can be conceptualized along a cooperativeconflictual dimension, where internal rebordering does not automatically threaten integration.Exploring the argument that the use of internal border controls is an indication of the member states' reduced trust in European cooperation and increased national focus, this article investigates the proposition that more extensive IBC use is associated with less confidence in the value of European cooperation.The present analysis found that, overall, increased focus on national control did not lead to a corresponding weakening of support for European integration.Member states did aim to secure their borders, but they did so while advocating for joint efforts to manage external borders and through communication at their shared internal borders.Thus, rather than a sign of disintegration, these findings support previous arguments that they should be understood as a reconfiguration of the European border regime towards cooperative but defensive integration.

European integration and the use of internal border controls
Ever since the initial stages of the European Union, the drivers of integration have been discussed as a balance between member states' need for efficiency and control.When becoming members, European states give up some of the control of their borders for the efficiency gains of belonging to the EU's internal market.Thus, integration through internal de-bordering, by the removal of political, economic, and practical border-barriers between member states has been at the core of the European project.If we understand the internal borders of the EU as sites where tension between national territorial control and European integration is at play, the introduction of internal border controls can be understood as a shift from prioritizing the efficiency of European integration to prioritizing sovereign territorial control.The Schengen Agreement shifts the responsibility of border control to the external EU borders.Thus, member states reintroducing internal controls can be an indication of loss of faith in the external bordering competencies of fellow Schengen states, or a critique of European cooperation as a whole. 1  The use of IBCs became an issue primarily in 2015, when they began to be used by several member states and with more long-term reintroductions than before.Before that, the use of IBCs was generally not problematized to the same extent.Up until 2003, the main reason for introducing internal border controls was for high-profile events such as meetings of heads of states or political gatherings such as protests and manifestations (Groenendijk, 2004).After the introduction of IBCs by several member states as a response to the refugee crisis in 2015, Austria, Denmark, France, Germany, Norway, and Sweden continued to prolong their border controls, long after the number of arrivals had dropped to pre-crisis levels.In their recent study of the framing of migration in the notifications for prolongations, Karamanidou and Kasparek (2022) argue that, among the five countries that prolonged their internal border controls from 2015 until 2019, the framing of migration shifted from threat-based to risk-based security arguments.There was a move from the urgency of action in the crisis of 2015 to a more preventive use of IBCs to ward off potential risks of border crossings, which challenged the intention of the Schengen Borders Code that internal controls are only to be used as a temporary measure.That the expansion of IBC use is seen as a challenge to the Schengen Agreement is not least clear in the European Commission's own analysis.In 2021, the Commission presented a proposal for amendments to the Schengen Borders Code in 2021 (COM/2021/891), which is yet to be adopted as law (as of October 2022).Among other things, this proposal aims to limit the use of IBC prolongations, for example by requiring more detailed risk-assessments by the member states using them.
When the coronavirus pandemic spread in the spring of 2020, one of the first measures taken by many states was to introduce border controls and close borders.Wolff et al. (2020) have described this as a 'knee-jerk' reaction to the perceived threat to public health.In their analysis of how EU institutions and member states frame this reaction, they conclude that, 'since the taboo of suspending Schengen had already been broken in 2015, the reactions to the pandemic could be presented as legitimate and consistent with previous efforts to manage cross-border "threats"' (Wolff et al., 2020).Thus, established as a legitimate policy tool, Wolff et al. (2020Wolff et al. ( , p. 1129) ) argue that internal border controls became more immediately available as a response to the spread of the coronavirus.These findings suggest that, discursively, there has been a normalization of the use of IBCs, even though they go against the core function of the Schengen area and, to an extent, suspend the principle of free movement of persons.The present article illustrates this 'normalisation hypothesis' by showing that IBCs have not only become more common, but also longer (less temporary) and more extensive in scope (in terms of borders covered) from the outset.
It has, however, also been argued that the migration crisis enabled further policy coordination at the supranational level (Falkner, 2016;Rhinard, 2019) and collective securitization of the Schengen Area (Ceccorulli, 2019).This crisis also prompted more external re-bordering, such as the creation of the new European Border and Coast Guard Agency or 'FRONTEX+' (Deleixhe & Duez, 2019), with a massive increase in budget during the last few years, from €6 million in 2005, to €142 million in 2015 and increasing to €543 million in 2021, as well as a projected increase in staff to 10,000 in 2027, including the 'Standing Corps' border guard (FRONTEX, 2021).This points to an overall development towards more border control in the EU.This is not unique to the European context but rather reflects a wider global development towards more border control as a go-to political solution, as states are spending increasingly more resources on border policing as well as border infrastructure (e.g.Schain, 2019;Simmons, 2019).From this perspective, the introduction of temporary internal border controls, which does (for the most part) take place within the established legal framework of Schengen, can be seen as an inherent part of the Schengen border regime, with member states showing a will to follow the rules agreed upon (Votoupalová, 2019).This echoes Zaiotti's analysis of earlier periods of crisis of Schengen, where crises 'represent cyclical adjustment mechanisms' that initially challenge but, ultimately, lead to regime adaptation rather than demise (Zaiotti, 2013).
In summary, three main interpretations or 'stories' about the consequences of internal border controls for European integration can be derived from previous research.First, the story about renationalisation: that the increased use of IBCs signals a renewed focus on national security and territorial sovereignty.This interpretation is connected to the story about disintegration: that the expanded use of IBCs signals a loss of faith in European cooperation and/or the end of the Schengen border regime.The third interpretation is a story about the reconfigured border regime: that the use of IBCs is part of the Schengen regime, and that challenges trigger regime change and new forms of cooperation, rather than disintegration.

Defensive integration and internal re-bordering as cooperation or conflict
An alternative analysis of the role of bordering for European integration is offered by Schimmelfennig (2021), who has developed a useful theoretical framework for understanding the tension between border control and integration.Integration, argues Schimmelfennig, should not be seen as onedimensional, i.e. as a question of internal de-bordering or re-bordering.Instead, successful integration must be understood as a combination of debordering, the removal of barriers to cross-border movement, at the internal borders, paired with re-bordering, the introduction of barriers to cross-border movement, at the external borders.Schimmelfennig (2021, p. 315) thus defines integration as the combination of internal cohesiveness and external demarcation.Seen in this way, internal re-bordering would only lead to disintegration if coupled with external de-bordering.Coupled with the strengthening of external borders, it instead results in what he calls 'defensive integration' (Schimmelfennig, 2021, p. 316).
As there have been major efforts towards external re-bordering of the EU since 2015, this article does not challenge Schimmelfennig's conclusion that we are seeing both external and internal re-bordering, and thus defensive integration.However, as some previous literature has discussed internal rebordering as a sign of disintegration in itself, the ambition here is to provide some qualification to the defensive integration argument by discussing the potential for disintegration that comes with how IBCs are used and justified by the member states.As bordering is a process rather than an either-or, an underlying assumption here is that internal re-bordering can be more or less likely to cause disintegration.
Drawing on border theory, territorial borders are here understood as constructed through the interplay of policies, practices, and perceptions toward them (Kolossov, 2005).The introduction of internal border controls therefore includes a range of factors that can affect the final result in terms of how disruptive they are to internal cohesiveness, including how IBCs are regulated, implemented, and perceived.To illustrate this, let us consider two scenarios.In the first one, controls are introduced for a short duration, implemented in cooperation with the neighbouring state, justified by what is perceived as a legitimate last resort reason, and do not involve a critique of European cooperation.This would be less disruptive both to political integration and to free movement than the opposite scenario, where controls are introduced for a longer time and implemented without coordination with neighbouring states, for what is perceived as an unclear or illegitimate reason, involving a strong critique of European cooperation.The latter scenario would present more of a challenge to integration, as it would be more disruptive both in practice and at the political level.
These two scenarios can be conceptualized as end points on a cooperative-conflictual dimension of the EU's internal border relations.Building on the idea of defensive integration, I argue that internal re-bordering that is at the cooperative end, coupled with external re-bordering, would be least disruptive to European integration.A more conflictual internal re-bordering, even when coupled with external re-bordering, could be said to emphasize the defensive rather than the integration part of 'defensive integration' and therefore be more problematic from a European integration standpoint.
Here, I argue that we can better understand the role of internal border controls for European integration by looking at how member states justify their use: when introducing IBCs, member states must make their intentions and reasons for doing so known to the EU and its fellow member states through mandatory notifications.These notifications are an opportunity for member states to signal their position vis-à-vis the rest of the Schengen Area and their commitment to European cooperation.If the introduction and continued use of IBCs are a sign of loss of confidence in European integration in general, or the principle of freedom of movement in particular, this should be observable in how member states make their arguments for introducing internal border controls.

Research design, materials and methods
To study the development of the use of temporary internal border controls, the member states' notifications of introductions and prolongations of IBCs, starting from 2006 and up until 2020, were analysed. 2These notifications contain information on the details of, and reasons for, each new introduction or prolongation of a temporary internal border control and are sent by member states to the European Council.The notifications, being mandatory messages that a Member State has to communicate when temporarily restricting free movement in Schengen, represent a rather specific type of text.It is communication 'among equals' (e.g. compared to domestic communication to political opponents or voters), it is directly from the policy maker (e.g. compared to media discourse about border policy) and it is systematic (in that its content follows a certain structure and contains both formal details and more or less elaborate justification arguments).This particular form of communication is important as it signals a Member State's intentions vis-à-vis the other members of the Schengen Agreement and the EU. 3 As such, this material is ideal for content analysis comparisons across time periods and subject matters.
The focus of the analysis was to find out: a) what message the member states send in these communications with regards to the status of European cooperation, and b) how these communications differ across time between periods of normalcy and crisis.The findings should indicate whether this communication points towards a renationalisation and disintegration, or towards a reconfiguration of integration in the Schengen Area.In total, 262 member-state notifications of internal border controls were included in the analysis. 4Figure 1 illustrates the distribution of these between 2006 and 2020.
For this article, the study of internal border controls between 2006 and 2020 is divided into four different time periods.The four periods in question were delineated based on the theoretical expectation that the use of IBCs in times of crisis will differ from 'ordinary' use, and thus include the two major border crises: the 2015 refugee crisis and the 2020 coronavirus crisis.The first period, 2006 to early 2015, represents the previous state of 'normality' in the area of free movement.During this time period, IBCs were introduced very sparingly.For the second period, when IBCs were introduced as a result of the migration crisis, the notifications between September 2015 and February 2016 are included, as this was the most urgent period of the crisis.After this period, no additional member states introduced controls due to refugee arrivals.The first country to introduce IBCs for the reason of migration or secondary movements was Germany in September 2015, and the last one was Belgium in February 2016.The third period analysed, between March 2016 and February 2020, represents an intermediate period between the two crises.During this time, the majority of IBCs were prolongations of those introduced during the second period, and very few new IBCs were introduced.The fourth and final period studied is between the first IBC introduced due to the coronavirus pandemic outbreak in March 2020, up until the end of 2020.The numbers of observations are distributed as follows: period 1 = 31, period 2 = 34, period 3 = 75, and period 4 = 122.During the two crisis periods, many IBCs are introduced within short periods of time, while the duration (number of days) of controls is much longer in the prolongations introduced since 2016 (see Figure 2).
The study was done making use of both quantitative and qualitative content analysis of the member states' notifications.Initially, a sample of 40 notifications, of which 10 were sampled from each of the four different periods, were analysed in depth to get a baseline understanding of how these documents were constructed.Overall, the notification documents follow a very standardized pattern, containing a main reason for the introduction of border control, some specifics of why they need to take this measure and a message to the EU institutions and other Schengen members, such as a greeting.A dataset of the 262 notification documents regarding IBC was then constructed.These documents were coded for variables such as start dates, end dates and the main reason stated for the border controls.Additional variables were constructed for whether the notification concerned the introduction of a new IBC, the prolongation of an existing one, and the number of bilateral borders that were included in the border control.
The qualitative part of the content analysis entailed a close reading of the documents and an analysis of how member states frame their relationship to the rest of the European community in these notifications.The question asked in this close reading was: in their notifications of decisions to introduce IBCs, how is the relationship between the Member State and the European Union framed?Framing refers to a process in which policy actors construct meaning in a policy-making situation, i.e. how an issue is 'made sense of' in the policy-making process (van Hulst & Yanow, 2016).Here, the focus of the analysis is how the relationship between the Member State and the EU is communicated in the arguments for the use of internal controls.As part of the Schengen rules, but in conflict with the core principles of freedom of movement, the use of internal border controls potentially destabilizes this relationship.Therefore, how member states frame their relation with the EU and its institutions when explaining their use of IBCs, can be used as an indicator of whether there are signals of waning confidence in (or even explicit critique of) the value of internal free movement in Europe.
For the quantitative part of the analysis, to test whether the increased use of border controls also indicates an increased national focus or reduced commitment to European cooperation, an index was developed by adding together four types of statements that emphasize European integration in relation to the use of IBCs.These were: commitment, operationalized as containing a statement about remaining committed to the functioning of the area of free movement; impact minimizing, operationalized as containing statements about IBC flexibility and/or a smooth passage for travelers and statements about facilitating the movement of goods; and cooperation focus, operationalized as statements about cooperation or coordination with other EU members when implementing the decision or that joint solutions to the underlying problem are needed.All of these statements were coded as 0 (not present) or 1 (present), and the total score (0-5) was recalculated as index values between 0 and 1.Finally, an index for renationalisation, operationalized as a composite of scores between 0 and 1 of statements emphasizing security of national territory, protecting one's own citizens and blaming shortcomings within Schengen or the actions of other member states, was also constructed.Coding these kinds of statements requires some degree of interpretation, as although these notifications are fairly similar in their constructions, there are variations in the language of similar statements.See Table 1 for example phrases.
By using both qualitative and quantitative analysis of the content of the internal border control notifications, we are able to identify both overarching patterns and developments over time, but also make note of particular details that characterize the different periods analysed.Gaining this insight is important, as IBCs have been used for a very wide range of purposes, from managing sports events to a global pandemic.

Analysis
Below, the empirical results are presented, first through the analysis of how the Member State -EU relationship is framed in the notifications of IBC in each period, after which the different periods of normalcy and crisis are compared.

Temporary internal border controls between 2006 and 2015
In the decade before the migration crisis, internal border controls were usually introduced in relation to major events such as high-level political meetings, with border controls set one or two days before and after the planned event taking place.The tone of the notifications from this period is primarily practical: they rarely contain any lengthier descriptions or explanations to justify the introduction of controls, or give any value-judgement of the notifying Member State's relation to the EU.Many notifications contain assurances that border guards will try to ensure the smooth processing of The notifications are written as letters, usually with, for example, the minister of the interior of the Member State as the sender, hence why they are often phrased as first-person statements, e.g.'I regret that … '.For the purposes of this article, the sender is assumed to be speaking for the Member State in question.
travelers, that the scope of controls will not be unnecessarily excessive and that controls will be flexible, indicating that member states are careful to show efforts to minimize the disruption to free movement that IBCs entail.This quote from the French notification dated March 30, 2009, contains two very typical statements for the period, an expression of gratitude for passing along the information and communication with the neighbouring country affected by the border control: I would be most grateful if you would pass on this information to the members of the Council of the European Union and to the States which take part in Schengen cooperation.
The French Government has contacted the German, Luxembourg and Swiss authorities to enlist their help in implementing this decision.(France 090330) This speaks to the general tone of member states' communication during this time.The notifications of temporary controls during this time thus frame the relationship between the member states and the European Union as unproblematic and friendly.No critique of the principles of free movement is visible, and thus internal border controls are communicated as practical solutions to temporary issues.Thus, before IBCs became a crisis of Schengen, the notifications describe them as a practical policy tool to temporarily increase security around specific events, often with bilateral cooperation in their implementation.As such, internal re-bordering during this period would clearly fall on the cooperation side of the cooperative-conflictual dimension.
The first period of crisis: September 2015 to February 2016 Following the arrival of record numbers of refugees in 2015, nine countries introduced internal border controls between September 2015 and February 2016.When member states first introduced internal border controls with the purpose of controlling the arrival of refugees in this period, their duration varied between 10 to 30 days.On average, the introductions in this period are 16 days longer than the previous period (see Table 2), and a couple of them mention a possible extension already in the first notice.In this period of uncertainty and urgency, the overall style of the notifications differs from the period before in that these notifications are much lengthier and have more elaborate and emphatic explanations for why the member states see the need to introduce IBCs.All of them mention that there is a serious threat to public policy and internal security, which is in line with wording in the Schengen Borders Code.Typically, the notifications focus on describing what is deemed to be the threat, often along the lines of 'unprecedented migratory pressure' (Norway 151126, Sweden 151112), 'uncontrolled migration flows', 'unmanageable flows of third country nationals' (Germany 150913) and 'massive influx' (Austria 150916).Arguments are made that the introduction of IBCs is a last resort because the Member State sees no other alternative.Germany and Austria, for example, state that their societies have seen a 'great willingness' to help but that this willingness is 'being strained' due to the increase in arrivals, and Norway and Sweden both state the reason for the introduction as that their authorities have reached the maximum capacity of what they can handle.Thus, at this point in time, introducing internal border controls does not seem to be a 'knee-jerk' reaction, but rather something the member states spend time explaining and justifying after having tried other options.
The relationship between the Member State and the EU or other Schengen members enters into the justifications of introducing border controls through references to measures that other states have taken, e.g. in Denmark's decision to introduce controls in January 2016, which states that: The Swedish, the Norwegian and the German Governments have already temporarily reintroduced border controls at their internal borders … Due to these measures set in place by our neighbouring countries and particularly the measures set in place by Sweden, Denmark is of now faced with a serious risk.(Denmark 160104) Other justifications reference what other member states have failed to do, as in this notification of Germany's decision in October 2015: No other Member State of the European Union is affected to such a degree.[…] the situation in Germany mainly depends on the measures taken by the responsible Member States to protect the EU's external borders.Unfortunately, I still have the impression that, despite European assistance, the necessary level of protection is not guaranteed.Moreover, transit countries within the Schengen area seem to be unable or unwilling to take the measures required by EU legislation to register and check each and every migrant.(Germany 151027) These types of arguments can be interpreted as a critique of the European cooperation, as member states acting uncoordinated in a way that negatively impacts other member states and 'forces their hand' in the introduction of controls.However, several also mention the need for EU Member State solidarity, the need to act together and the common responsibility.Overall, there are mixed signals about the status of European cooperation in these notifications: although solidarity is emphasized, it is also clear that countries either feel they have done more than their share (e.g.Germany, Austria) or that the actions of others have put them in this situation (e.g.Denmark, Belgium).

The interim period: March 2016 to February 2020
After migration dropped substantially in 2016, Austria, Germany, Denmark, Norway, Sweden, and France continued to prolong their internal border controls each time the previously defined duration was coming to an end.In 2016 and 2017, the Council adopted several implementing decisions, which recommended member states to keep their controls for a longer period of time (three to six months at a time).Following the implementing decisions, member states' notifications of controls are very brief.Several, but not all, do not specify a reason for the need to prolong the IBCs other than that they do so in line with the Draft Council Implementing Decisions.For those that provide elaboration as to why internal border controls are deemed necessary, a reoccurring argument is that internal border controls are due to shortcomings at the external Schengen border.This type of statement could be seen as an indication of member states' lack of confidence in the management of the external border, as for example in this statement by Denmark: … persistent shortcomings and structural deficiencies at the EU external borders as well as the fact that the Dublin regulation is still not applied by all Member States facilitate significant irregular secondary migration.(Denmark 171112) Or, for example, this statement by Austria in February 2017 that demonstrates how the solution to abandoning internal controls lies at a more consolidated external border: A fully functioning protection of EU external borders is a minimum requirement for having a European domestic area without border controls.(Austria 170211) In short, internal re-bordering is justified by the lack of external bordering.These arguments from the member states reflect a development that has already been observed, which is that since 2015, the EU has taken several measures to expand the external border control capacities of both the member states with external borders and via the shared European institutions.
As described by Karamanidou and Kasparek (2022), the main motivation for internal controls was reframed in the interim period, from focusing on the arrival of migrants to an emphasis on the risk of terrorist attacks.In the notifications, this risk is often framed as a general European security problem, but one that makes IBCs necessary for the particular Member State.As Council Recommendations had ended in the autumn of 2017, and the arrival of refugees had been reduced to pre-2015 levels, member states prolonging controls are careful to express their continued commitment to Schengen, for example in this note from Denmark in November 2018: Dear colleagues, Schengen is one of the most cherished achievements of European integration, and the Danish Government supports the goal of returning to an area without internal border controls as soon as possible.(Denmark 181112) After the council recommendations ended in 2017, the member states who keep prolonging their IBCs (assumedly) know that they are acting in opposition to the Schengen rules, and therefore, their justifications were lengthier and contained more detailed situational descriptions for why they wished to prolong controls.In some notifications, statements of commitment to Schengen are followed by assessments that the state is not likely to remove IBCs in the near future.This supports the interpretation of some scholars that the use of internal border controls, especially in this extensive way with prolongations being renewed for several years, indicates a loss of trust in the capacity of the European Union to control its shared external borders.But this is paired with efforts to make commitments of faith in European cooperation, e.g. to 'remain committed to the goal of returning to an area without internal border controls and a well-functioning Schengen cooperation' (Sweden 180512).These kinds of statements are efforts to rhetorically establish an ambition to uphold the freedom of movement in Schengen, even when continuing internal controls.Overall, the tone in these notifications is more apologetic, and the explicit support for a Schengen Area without internal border controls emphatically expressed, which can be interpreted as an effort on part of the member states who continue to prolong their IBCs to balance this measure with explicit vocal support for cooperation, for example in joint efforts to strengthen the control capacity at the external border.

The second internal border crisis: the coronavirus pandemic in 2020
In the spring of 2020, the coronavirus began to spread rapidly and, as a response, 17 Schengen states introduced internal border checks as one of their measures to reduce the spread of the virus.Out of the 14 members of the EU that introduced IBCs, three of them did so for the first time.The notifications from this period are overall similar to one another.Most describe the pandemic as a serious threat to public health, internal security and public order, and thus have a reason to introduce temporary internal border controls as stipulated in the Schengen Borders Code (2016, art 28).Many of the member states' notifications contain a statement about this being a necessary, proportional and effective measure to contain the spread of the virus.Most of the notifications also contain a variation on the phrase '[t]he scope and intensity of the planned border controls will not exceed what is required by the current security needs' (Hungary 200312).There are some examples where the interest of the Member State is explicitly about protecting the national territory, as in the case of Slovakia: 'to significantly reduce the spread of this very dangerous coronavirus to the territory' (Slovakia 200313).However, more often, the pandemic is described as a risk to the whole European area, and the introduction of border controls is described as an action that has been agreed with countries concerned (Austria 200314), and that 'authorities will work closely with the authorities of neighbouring countries' (Belgium 200320).
The relationship to the neighbours thus seems to be more coordinated than in the 2015 crisis, when countries sometimes framed their IBCs as a consequence of other member states' border controls or shortcomings at the external border.Here, more coordination between member states is communicated, and other member states' shortcomings are not provided as a reason for controls.Moreover, many of the border control notifications in 2020 contain a focus on maintaining the internal market by allowing for the movement of goods: 'every effort will be made to allow goods to move largely unimpeded across borders' (Germany 200319), and exempting frontier workers and healthcare professionals from border restrictions (Spain 200327).
Most member states that reintroduced internal controls due to the pandemic stopped prolonging them in the latter half of 2020.In addition to those countries that have had prolongations of internal controls due to migration since 2015, only Finland and Hungary were prolonging their controls stating coronavirus as the only cause.In the prolongations in the second half of 2020, member states that had prolongation of controls already (pre-pandemic) often include more than one reason for continuing internal border controls, stating both risks of terrorism, the coronavirus, and secondary migration as reasons for prolongation (e.g.Denmark 201112, Germany 201112).
A notable difference between this period compared to the two previous periods is the different target of the controls.As was observed in the previous two periods, the target of IBCs during the migration crisis is often stated as an ambition to control the 'massive influx'.In the third period, there is a shift towards discovering 'potential terrorists' as a reason for using controls.During the pandemic, in contrast, the 'virus' is the target, not a specific group of people or people carrying the virus.Therefore, the controls during this time are described in the notifications as much more comprehensive (this is the only time that notifications contain information about certain border crossings closing completely).In short, the objective during this time is to substantially reduce cross-border movement altogether.

Comparing fifteen years of internal border controls
As has already been established, the use of internal border controls has expanded in periods of crisis, and, for the member states that introduced them as a response to refugee arrivals in 2015, prolongations extend far beyond what the Schengen rules for temporary internal controls originally intended.The sheer increase in numbers of IBCs used suggests that the taboo of using internal border controls indeed was broken in 2015 (Wolff et al., 2020).But does this mean that the format of these controls also changed?One way to estimate if the use of internal border controls in the refugee crisis and their subsequent prolongations have also impacted the format of IBCs is to see if they are now introduced for longer periods from the outset and if they are more extensive in scope.If we look at the correlation between the date of introduction and the duration, but exclude prolongations to only look at new introductions, there seems to be ahowever smalltrend towards somewhat longer durations when new border controls are introduced (Figure 3).
The scope of border controls being implemented does not follow a clear linear pattern: for border controls that were primarily aimed to reduce the number of arriving refugees, the average number of borders that the controls apply to is less than in the first period and in the pandemic period.During the COVID-19 crisis, 86 per cent of the notifications studied concerned two or more (often all) borders, whereas only 65 per cent do so between 2015 and 2019, which is lower than in the pre-refugee crisis period (Table 2).This difference speaks to the different causes of the border controls being introduced: during and after the refugee crisis, member states who were transit or destination countries were primarily focusing on borders where arriving migrants were passing through, and these often concern very specific border crossing points.During the coronavirus pandemic, on the other hand, although some of the initial IBCs specifically deal with travelers from highly affected countries, e.g.Italy, after some time, as infections rose across the board, more general travel restrictions were put in place, including controlling all borders rather than specific border crossing points.
Two of the main interpretations derived from previous literature on internal re-bordering, set out at the start of this study, were that the use of internal border controls signals a renewed focus on national territorial control (i.e.'renationalisation') and that this development also signals a move away from European integration (i.e.'disintegration').The alternative interpretation proposed was that a renewed emphasis on internal border control reflects a more general re-bordering development and does not coincide with less European commitment among member states ('reconfigured border regime').No significant correlation between year introduced and level of EU-confirming statements was found.When performing an Anova analysis of the difference in mean score of the integration index between the four periods, no significant differences were found.That is, on average, member states' notifications of IBCs do not contain less statements emphasizing the values of commitment to cooperation and free movement now than they did before the use of IBCs expanded in 2015.
There is some support for interpreting internal re-bordering as a sign of renationalisation.Since 2016, in the third and fourth periods analysed, there is on average a higher level of national focus than in the first period (before the migration crisis).However, as already noted, this development is not paralleled with a corresponding weakened European focus.For internal re-bordering to be interpreted as both a renationalisation and a disintegration development, an increased focus on national needs would have coincided with a decrease in commitment to European integration.This has not been found to be the case.Indeed, for this to be fully supported, we would expect to see a negative correlation between the scores on the European integration index and the renationalisation index.The difference between period 4 and periods 2 and 3 is significant at the 0.05 level.b The differences between periods 3 and 4 to period 1 are significant at the 0.05 level.
Instead, that correlation is positive (B=0,097, SE=0,052, p= 0,064), which means that more national focus does not per definition signal a lack of commitment to the EU.

Discussion
The results of this analysis show the complexity of the matter of national border control in the internal EU context.The trend is towards longer duration and wider scope of controls over time, which is in line with the idea that the use of IBCs has become normalized (Wolff et al., 2020).It is also clear that there are qualitative shifts taking place between each of the four periods studied.The 'old normal' of the years before 2015 seems, in light of later development, very uncomplicated.Short duration, often with bilateral cooperation mentioned, and done for very specific reasons, puts the use of IBCs during the first period clearly on the cooperative side of internal border relations.In later periods there are some elements that would fall more towards the conflicting side, such as the critique against the external border controls during the refugee crisis, the extensive duration of controls during the interim period and the more extensive scope during the COVID-19 crisis.
Overall, however, and somewhat surprisingly, when looking at the development across the four periods, there were no significant differences on the European integration index, despite an increase in renationalisation emphasis in the last two periods.This consistency over time disputes the idea that with more use of IBCs, or more national focus, follows less commitment to European integration.Instead, this is more in line with a cooperative type of internal border relations.While aiming to secure their borders, member states are advocating for joint efforts to manage external borders, and often mention cooperation in the implementation of controls.Thus, the findings of this article to some extent confirm previous observations that states see IBCs as a policy option made possible by, rather than a threat to, the Schengen regime (Votoupalová, 2018).
Although the conclusion of the present analysis thus found no major differences between the periods of crisis when it comes to the level of support for European integration, there are differences between these crises that require further reflection.During the refugee crisis, the intention of internal border controls was to stop a specific group of people, i.e. asylum seekers, from being able to cross the border in order to reduce the number of arrivals.During the interim period, controls were argued to be needed to stop 'potential terrorists'.When IBCs targets a specific group, it can potentially have a very different impact on Schengen Area citizens, depending on whether one can be identified as belonging to the ethnic majority population or not.This dilemma cannot be covered by the analysis here, but the use of profiling in the implementation of internal border controls has been studied elsewhere (Casella Colombeau, 2017;van der Woude & van der Leun, 2017).Depending on how these long-term, 'flexible' controls are carried out, they risk working in a discriminatory manner when targeting only some border-crossers.
In contrast, the internal border controls introduced during the COVID-19 pandemic to a much greater extent targeted border-crossers in general, as the intention was not to stop a specific group of people but to restrict movement and, thus, potential spread of the virus altogether.These controls, therefore, to a greater degree reduced free movement within the Schengen Area.Yet, as they were more temporary, they may have less of a long-term impact.The sheer number of internal border controls used in 2020 does indicate that they have been established as a readily available policy tool.It remains to be seen how the proposed amendments to the Schengen borders code will change how IBCs are used.
To truly assess the extent to which internal border controls will affect European integration and the principle of freedom of movement in the Schengen area, future research should focus on analysing the practical implementation and impact of the IBCs on cross-border movement in Europe.How these border controls function in practice will impact the material effects they have on cross-border communication, for example, the extent to which people are able to commute across the internal borders of the European Union.As freedom of movement is at the core of what EU citizens value in the EU cooperation, understanding the impacts of IBCs on everyday crossborder activities will further inform the extent to which the internal re-bordering also implies disintegration.

Notes
1.The end-point of such a critique against European cooperation would be the withdrawal from the Schengen Agreement altogether.Although the United Kingdom (UK) was not part of the Schengen Agreement, Brexit can be understood as an example of this, as it was, in part, driven by arguments about the UK's need to 'take back control' of its national borders.2. As the Schengen Borders Code regulations in their current form (amended in 2016) were established in 2006 (Regulation 562/2006 of the European Parliament and of the Council), this year is used as the starting point for the analysis in the article.3. It is likely that renationalisation framings are more emphasized in domestic contexts.Most important for the purposes of this study, however, is how communication on the use of internal border controls develops over time, as the objective is to test the assumption that we are seeing more renationalisation and less integration over time within this specific means of communication between member states.4. The total number of notifications of temporary internal border controls in this time period is somewhat higher than 262, but hard to determine for certain.The official list of Member State notifications is published by the Commission (European Commission, 2021) and contains 244 notifications between 2006 and 2020.That list does however have some numbering inconsistencies.The full list used here is based on the notification documents that were retrievable through the Public Register of Council documents, online or upon request.Some of the notifications documents from the official list were not found, and those are therefore excluded from the analysis here.

Figure 1 .
Figure 1.Member States' notifications of introduction or prolongation of temporary internal border controls by main reason for the introduction.

Figure 2 .
Figure 2. Duration (days) per internal border control notification.Vertical lines mark the start of periods 2, 3 and 4.

Figure 3 .
Figure 3. Correlation between start date and duration of new internal border control introductions.

Table 1 .
Content analysis variables.Please let me once again assure you that I do remain committed to the goal of returning to an area without internal border controls and a well-functioning Schengen cooperation as soon as the situation allows.'(SWE191112)Impactminimizing Flexible and/or smooth passage for travelers 'The aforementioned checks will be flexible and geared to the situation'.(SPA 090926) 'All measures will be taken to ensure that border control activities during this period will not obstruct the smooth processing of travellers'.(MAL 151109) Facilitate movement of goods 'With a minimum impact on other public interests, in particular the unhindered movement of goods.
'' (SLK 200508) Border control cooperation Bilateral cooperation on border control '[A]fter careful consideration and in consultation with the Republic of Austria, I have … ordered the temporary reintroduction'.(GER 201112) 'We are in constant consultations with our partners and build on many years a

Table 2 .
Mean values across the four periods of internal border controls.