Gary Gates, a demographer at the Williams Institute at the UCLA School of Law who researches sexual orientationlaw and public policy, says the state itself would see a "noticeable economic benefit" from legalized same-sex marriage.
But politicians from both parties, as well as President Clinton, would like to see the law extended to cover sexual orientation, gender and disability.
She said she would work to pass a federal law outlawing employment discrimination based on sexual orientation and propose another measure extending benefits to the partners of federal employees.
Mr Panetta said that while the remaining benefits are blocked by a federal law that does not recognise same-sex marriage, he foresaw a time "when the law will allow the department to grant full benefits to service members and their dependents, irrespective of sexual orientation".