In Canada, as elsewhere, the norms of capitalist legality include an aversion to permitting collective action by sellers of commodities to increase their price. Labour law, however, is built on the norm of freedom of association and the right of commodified workers to combine for the purpose of improving the terms of their labour contracts. This gives rise to a recurring regulatory dilemma. In Canada, this conflict has been resolved by granting workers a legal immunity from liability under competition law for engaging in approved collective action to improve or defend their terms and conditions of work. However, the zone of toleration is contestable at three margins, explored in this chapter. First, is the margin between those workers who are covered by the exemption and those who are not; second between the sale of labour power and the sale of the commodities it produces; and the third is between the means that covered workers can lawfully use to make their combinations effective and those that take them out of the zone of toleration. The chapter explores the history of the construction of the zone of toleration and the conflicts over its margins, which are currently stable.