The lawsuit says many servicewomen are, in fact, engaging in combat. But that the government turns a blind eye to that.
"We found ourselves in ground combat, taking fire for about 20 minutes from the enemy," Maj. Mary Jennnings Hegar said.
Jennnings Hegar is a combat search and rescue pilot in the Army National Guard. She received a purple heart for injuries sustained when her chopper was hit by ground fire.
"I received shrapnel wounds on my face, my arms and a burn on my back," Staff Sgt. Junnifer Hunt said.
Hunt has been an Army reservist for a decade. She received injuries in Iraq, when her Humvee was hit by an improvised explosive device.
All four servicewomen who filed suit had combat experience despite the Defense Department policy. All did tours in Iraq and Afghanistan. They say in modern warfare, the front line is everywhere.
"Anytime a woman or, for that matter, any service member sets foot in Iraq or Afghanistan, they are serving in a combat zone," Marine Corps Reserves Capt. Zoe Bedell said.
But the suit says the military is not dealing with reality.
"Because of the policy, women are not often officially part of the all-male units they're going on missions with," ACLU attorney Ariela Migdal said.
"The combat exclusion policy is one of the last vestiges of federal government policy that presumes women are less capable than men just because they are women," ACLU attorney Elizabeth Gill said.
Women make up 14 percent of active military personnel; 280,000 of them served in Iraq and Afghanistan. The plaintiffs say the ban puts them at a disadvantage for promotions and recognition.
Earlier this year, the Defense Department opened about 14,500 positions to women that had previously been limited to men. A regulation that banned women from living with combat units was also lifted, but not the ban on serving in combat.
Here are two different reactions from two older veterans.
Men and women are equal so they should be equal in all forms and all areas," Air Force veteran Earl Leslie said.
"I don't want to see that; I'm not the best person in the world but I don't want to see them die and that's about the truth of it all," Army veteran Michael Mann said.
Pentagon Press Secretary George Little said Tuesday the Defense Department was making strides in allowing more women into combat. He didn't comment specifically on the lawsuit but said Secretary Leon Panetta's record on women in combat is "very strong."