418 is a famous Supreme Court of Canada decision on equality rights under section 15 of the Canadian Charter of Rights and Freedoms where the Court found "marital status" was an analogous ground for discrimination (i.e., a characteristic which cannot legally be the basis for discrimination under section 15).

Miron suffered a car accident and attempted to claim the injuries under his partner's insurance policy.

However, the Ontario Insurance Act provided that benefits were only available to spouses who were legally married.

Chief Justice Lamer criticized Ontario counsel's refusal to defend the legislation and ordered Ian Binnie, a future Supreme Court justice to defend the legislation in place of and at the cost of the Ontario government.

The finding that common law marriages are protected by section 15 was repeated in Nova Scotia (Attorney General) v. Walsh (2002) and Hodge v. Canada (Minister of Human Resources Development) (2004).