Mexico's Supreme Court ruled Tuesday that all 31 states must recognize same-sex marriages performed in the capital, though its decision does not force those states to begin marrying gay couples in their territory.
In a 9-2 decision, the tribunal cited an article of the constitution requiring states to recognize legal contracts drawn up elsewhere.
It did not specify what degree of recognition must be granted to same-sex couples.
Mexico City's same-sex marriage law, enacted in March, extends to wedded gay couples the right to adopt children, to jointly apply for bank loans, to inherit wealth and to be covered by their spouses' insurance policies. Some of those may end up applying only in the capital.
The Supreme Court ruled last week that same-sex weddings are constitutional - though it is holding separate discussions this week on the adoption clause.
One of the justices, Sergio Aguirre, argued against adoptions by same-sex couples Tuesday, saying children might suffer discrimination as a result.