SAN FRANCISCO — Four female service members filed a lawsuit Tuesday challenging the Pentagon’s ban on women serving in combat, hoping the move will add pressure to drop the policy just as officials are gauging the effect that lifting the prohibition will have on morale.
The lawsuit, filed in federal court in San Francisco, is the second one this year over the 1994 rule that bars women from being assigned to ground combat units, which are smaller and considered more dangerous since they are often in battle for longer periods.
The legal effort comes less than a year after the ban on gays serving openly was lifted and as officials are surveying Marines about whether women would be a distraction in ground combat units.
‘‘I’m trying to get rid of the ban with a sharp poke,’’ said US Army Staff Sergeant Jennifer Hunt, who was a plaintiff in the latest lawsuit and was injured in 2007 when her Humvee ran over an improvised explosive device in Iraq.
Hunt and the other three women said the policy unfairly blocks them from promotions and other advancements open to men in combat. Three of the women are in the reserves. A fourth, Marine Corp Lieutenant Colleen Farrell, leaves active duty this week.
The lawsuit alleges that women are barred from 238,000 positions across the Armed Forces.