"I served five months past my one-year obligation and I feel that it's time to let me go back to my wife," David Qualls told a news conference.
Qualls and seven other reserve members filed a suit in federal court seeking a judge's order to require the Army to immediately release them from service.
Other soldiers have filed similar suits over the past year, but this was believed to be the first by active duty service members.
Under the Pentagon's "stop-loss" program, the Army can extend enlistments during war or national emergencies as a way to promote continuity and cohesiveness.
The policy, invoked in June, could keep tens of thousands of personnel in the military beyond their expected departure. The policy was also used during the buildup to the 1991 Gulf War.
Qualls signed up in July 2003 for a one-year stint in the Arkansas National Guard but has been told he will remain on active duty in Iraq until next year.
The lawsuit contends the policy is a breach of the service contract because it extends the length of service without a soldier's consent. It also alleges the contracts were misleading because they make no reference to the policy, said Staughton Lynd, an attorney for the soldiers.
Lt. Col. Bryan Hilferty, an Army spokesman, said he could not respond to the lawsuit because the Pentagon had not yet reviewed the filing, but he defended the policy as necessary to maintain cohesive units in the war on terror.
"The alternative is people start leaving that unit in the middle of a tour," he said.
Qualls, the only plaintiff who is publicly identified, is home on leave. The other seven, listed as John Does to protect their privacy, are now serving in Iraq or are in Kuwait en route to Iraq, Lynd said.
Qualls and two other plaintiffs enlisted under one-year "Try One" contracts that have expired. Four others are serving under multiyear contracts that also have run out. The remaining soldier's contract doesn't expire until spring, but he has been told to expect to serve in Iraq beyond the expiration date.
The lawsuit names Defense Secretary Donald Rumsfeld and other Army officials.