On a blast-furnace of a day when normally chilly San Francisco hit 96 degrees, the California Supreme Court enhanced its reputation as a trail-blazing institution Thursday by giving gays and lesbians the right to marry.

“The California Constitution,” Chief Justice Ronald George wrote in the 4-3 ruling, “properly must be interpreted to guarantee this basic civil right to all Californians, whether gay or heterosexual, and to same-sex couples as well as to opposite-sex couples.”