At last, a federal judge — and one appointed by a Democratic president — has issued a ruling on same-sex marriage based on the U.S. Constitution, rather than politics.In a remarkable decision, Judge Juan Perez-Gimenez, who was nominated to the U.S. District Court for the District of Puerto Rico by President Jimmy Carter, upheld Puerto Rico's law defining marriage as the union of a man and a woman, concluding that there is no constitutional right to same-sex marriage.