The Obama administration is appealing a federal court ruling that orders the Pentagon to stop enforcing its ban on gays serving openly in the military.

Allowing the California judge's ruling to be implemented immediately "will irreparably harm the public interest in a strong and effective military," the government argues in court papers.

In the meantime, the Pentagon has said it will comply with the court order, which was issued this week in a lawsuit brought by opponents of the 17-year-old law.

Here, in question-and-answer form, is a look at the "don't ask, don't tell" policy.

Q: What does the law say and when was it adopted?

A: It was imposed by a 1993 law intended as a compromise between President Bill Clinton, who wanted to lift the ban on gays in the military, and a reluctant Congress and military that said doing so would threaten order.

Under the policy, the military can't ask recruits their sexual orientation. In return, service members can't say they are gay or bisexual, let it be known that they engage in homosexual acts or marry a member of the same sex.

Q: How many people have been kicked out of the military because of the law?

A: More than 13,500 service members have been dismissed under the law. Annual rates of discharges have declined dramatically in recent years. In 2001, the military dismissed 1,227 troops for being openly gay. In 2009, only 428 were let go.

The rapid decline could be attributed to repeated combat deployments that have made it more difficult to turn away volunteer troops. Repeal advocates say increased acceptance among the rank-and-file also plays a role.

Q: Why did U.S. District Judge Virginia Phillips rule against the "don't ask, don't tell" law?

A: Phillips said it violates due process rights, freedom of speech and the right to petition the government for redress of grievances guaranteed by the First Amendment.

She said it doesn't help military readiness and instead has a "direct and deleterious effect" on the armed services by hurting recruiting when the country is at war and requiring the discharge of service members with critical skills and training.

Q: The Obama administration says it is in favor of repealing the law. Why did it challenge the court's ruling?

A: The Justice Department court papers filed Thursday said letting the judge's ruling go forward immediately would be a major problem for the military. Properly implementing any change in policy would be "a massive undertaking" that "cannot be done overnight," the Justice Department said.

The department said repeated and sudden changes regarding "don't ask, don't tell" would be "enormously disruptive and time-consuming, particularly at a time when this nation is involved in combat operations overseas."

Q: Is it now safe for gays in the military to say they are gay?

A: No. The Pentagon has said it will comply with the court's order for now and lift its ban on service by openly gay troops. But if a judge grants the Justice Department request for a temporary stay on the order while it is being appealed, it is assumed that the Pentagon would revert back to its original policy toward gays.

Legal experts say they aren't sure what would happen to service members who said they were gay after the law was suspended but before it was reinstated.

Q: Most Americans don't seem to care whether gays serve in the military. Why is the military resisting?

A: Polls show that most Americans think gays should be allowed to serve openly. And for the first time, the Pentagon's top leadership — Defense Secretary Robert Gates and the Joint Chiefs of Staff chairman, Adm. Mike Mullen — agree.

But military leaders remain concerned because the military recruits heavily from populations that fiercely oppose openly gay service and worry that making changes too soon would prompt a backlash. Pentagon officials also say they need time to figure out the particulars, such as whether gay and straight troops would share barracks and whether the military should provide benefits to gay partners.

Q: Is the case headed for the Supreme Court?

A: Timing is everything in politics and so it is here. If Congress overturns "don't ask, don't tell" sooner, as the Obama administration says it wants, rather than later, there may be no need by either the government or the Log Cabin Republicans who brought the lawsuit to seek Supreme Court review. If Congress won't act, the Supreme Court could be asked to step in by the government, the plaintiffs in the case or both.