SAN FRANCISCO (AP) ‚?? Four female military service members have filed a lawsuit challenging the Pentagon‚??s ban on women serving in combat. The lawsuit was filed in federal court in San Francisco Tuesday and is the second such federal challenge filed by female service members this year. The latest demands the lifting of the military‚??s so-called combat exclusionary policy that applies to all women. The lawsuit alleges the ban on a single gender violates constitutional equal protection rights and unfairly blocks women from promotions and other advancements open to men in combat. Further, the lawsuit alleges that women are already serving unofficially in combat units. Two of the four women who filed the lawsuit have received Purple Heart medals for injuries sustained in Afghanistan. The women are represented by the American Civil Liberties Union.