Arguments in the case known as Obergefell v. Hodges began at 10am, and a decision, due by the end of June, will determine whether gay marriage will be legal nationwide in North America. The hearings entail plaintiffs forbidden to marry in Kentucky, Michigan, Ohio and Tennessee, four of the 13 states that currently prohibit same-sex marriage.

The lead plaintiff, James Obergefell, was legally married in Maryland to John Arthur, who was listed as single on his death certificate after he died at home in Ohio.

The outcome of the hearings comes down to what at least five of the nine Supreme Court Justices conclude the words “equal protection of the laws” and “due process of law”—rights provided but not defined by the 14th Amendment—mean for same-sex couples in 21st-century America.

Their decision will affect not just the right of gay people to marry in America, but also their right to be recognised as a spouse or parent on birth and death certificates and other legal documents.