As the US Supreme Court appears poised to make a ruling on two cases around equal marriage, here is a short history of the legislation and a breakdown of the six possible outcomes the court might make.

After the California Supreme Court ruled in 2008 that gay couples have a constitutional right to marry, Proposition 8 was approved in state elections in November of that year, specifying that marriage is “only marriage between a man and a woman is valid or recognized in California.”

Prop 8 did not affect domestic partnerships or same-sex marriages which were held in California before November 2008.

Following demonstrations, and protests against Prop 8, the California Supreme Court challenged the legislation, and upheld it, but allowed existing same-sex marriages to remain.

In 2010, the United States District Court ruled that Prop 8 was unconstitutional, and issued an injunction against enforcing it.

The US 9th Circuit Court of Appeals also affirmed that Prop 8 was unconstitutional in 2012.

With this potential ruling (or non-ruling), a decision by the Supreme Court could have one of six possible outcomes.

  • The court could uphold Prop 8, leaving the California ban on equal marriage intact. The next step for equal marriage advocate would then be to attempt to return to having voters re-legalise equal marriage.
  • A strike down of Prop 8, and the issuing of a broad ruling, which would find that any state ban on same-sex marriage is unconstitutional. This would be the most far-reaching outcome, and would effectively allow equal marriage across the US.
  • The court could invalidate Prop 8, but let the Court of Appeals’ ruling stand, which would allow same-sex marriages to resume in California, possibly a month after the ruling.
  • A strike down of Prop 8 which finds that states such as California that provide equal benefits to same-sex couples, must allow marriages in order to comply with federal equal protection rights. This decision would apply to California, as well as seven other states with domestic partner laws and civil unions for same-sex couples.
  • In the most confusing outcome, the court could find that the supporters of Prop 8 never had the right to defend the law on behalf of the state, following the 2010 ruling that it was unconstitutional. This would lead to further legal battles over the scope of the ruling, and whether it applies across the state.
  • The Supreme Court could rule that it never should have accepted the case for review. This would also allow the Appeals Court ruling to stand, effectively striking down Prop 8, and allowing same-sex marriages to resume in California.

It is unclear which ruling the Supreme Court will make, with some arguing it is likely to strike down Prop 8, and others arguing that there is a long legal battle ahead until equal marriage is legal across the US.

The Supreme Court will not make a ruling today, and the next possible date for a decision is Monday 17 June.