Three highly-decorated gay service members discharged under “Don't Ask, Don't Tell” have filed a lawsuit challenging the law.

The plaintiffs – Michael D. Almy, Anthony J. Loverde and Jason D. Knight – are being represented by Servicemembers Legal Defense Network (SLDN), the largest group lobbying for repeal of the 17-year-old law that bans gay and bisexual troops from serving openly.

Aubrey Sarvis, the group's executive director, said he hoped the lawsuit would increases the pressure on lawmakers to lift the ban this year.

“This filing is a shot across the bow as we prepare to pursue and sustain an aggressive far reaching litigation strategy if the Senate fails to act this month to repeal the law. This dispute can be resolved by Congress or by the courts,” Sarvis said in a statement.

“With this filing we put Congress on notice that a cadre of service members and our national legal team stand ready to litigate strategically around the country,” he added.

In their suit – filed Monday in U.S. District Court in San Francisco – plaintiffs, who together have served 25 years in the military, are asking for their reinstatement and for the law to be declared unconstitutional.

The Obama administration is currently appealing two federal rulings against the law. The Ninth U.S. Circuit Court of Appeals in California is preparing to hear the government's appeal to U.S. District Judge Virginia Phillips' September ruling striking down the law as unconstitutional. Following her ruling, Phillips issued an injunction ordering the government to stop enforcement of the law, but the appeals court set the ruling aside after 8 days, and the policy returned.

Defense Secretary Robert Gates has urged senators to act against the law during the lame-duck session of Congress or risk leaving the military “at the mercy of the courts and all of the lack of predictability that that entails.”

Gates made his remarks last week after Senate Republicans blocked a defense bill – which included language to repeal the law – from moving forward. A group of bipartisan senators have launched a last-ditch effort to end the law with a standalone repeal bill.

Sarvis added that his group is working on two additional challenges to the law, including one on behalf of young people who have been deterred from entering the military because of the prohibition.