Canada’s coal-fired electricity regulations were published in 2012 and were the first federal regulations targeting greenhouse gas (GHG) emissions from stationary sources. They have since been strengthened. This case study tells the policy story of how the regulations came about, and how in the space of 18 months the government’s regulatory approach evolved from one based on emissions intensity, to cap-and-trade, to capital stock turnover. It also tells the technical story of how a simple regulation based on the length of time a facility has to operate can still build in elements of trading and other flexibilities. It ends with some observations around lessons learned.