Populations of blue whales were heavily depleted across the globe by industrial whaling and are still considered globally endangered today. In the Northwest Atlantic, an estimated 400–600 individuals remain, but these numbers are highly uncertain. Ship strikes, fishing gear entanglement, and marine debris are thought to be leading causes of contemporary human-caused mortality in blue whales, with anthropogenic noise possibly causing sublethal stress and injury. Climate change is recognised as an emerging and intensifying threat that is likely to affect food supply and could limit the capacity of the population to recover. Both Canada and the United States have protected blue whales through their domestic legislation. This article reviews law and policy responses in the two countries, as well as bilateral, regional and international frameworks that address anthropogenic threats to blue whales. Future scientific directions, as well as recommendations for improvements to domestic legislation and multilevel cooperation are outlined.