This is no theoretical debate. A new federal law, slipped unobtrusively into a spending bill in September, says that anyone convicted of even a misdemeanor in a domestic-violence incident–ever–is prohibited from owning, carrying or transporting a gun. The law was widely praised then as a quick and easy way to curb an escalation of violent acts against wives and children–and if a cop got caught up, so be it. It also plugged a legal loophole; while felons were already barred from owning guns, most domestic-abuse cases are prosecuted as misdemeanors.

But so far, just about the only people giving up their guns are the cops. A dozen or so officers, in cities including Los Angeles, Denver and Detroit, have turned in their guns and been demoted to desk jobs–or told they might be fired. In Minneapolis four officers, two of them highly decorated, have been reassigned to desk duty or put on paid leave. “If you can’t carry a gun you can’t be a cop,” said Police Chief Robert Olson. Denver’s sheriff’s department came up with a skirt-the-issue solution: it asks deputies with a misdemeanor record to hand in their guns before going home.

How many law-enforcement officers might be affected? There are about 700,000 at the federal, state and local levels, so it could reach into the thousands. In re-cent weeks law-enforcement agencies have scrambled to search their personnel records for convicted officers, though it’s not always useful; some states don’t list misdemeanors on rap sheets. The Justice Department is relying on the honor system. It has asked all employees who carry firearms, including FBI and Drug Enforcement Administration agents, to declare in writing that they’ve never been convicted of a misdemeanor involving domestic abuse–or to turn in their weapons. The Pentagon admits it’s not in compliance while it drafts new regulations. How many soldiers might be past abusers is anyone’s guess.

Many law-enforcement agencies generally support the law. But not surprisingly, police organizations and unions aren’t happy. They are complaining that the law is unenforceable and may be unconstitutional. Says Los Angeles County Sheriff Sherman Block, “This takes away the police officer’s ability to make a living.”

Up to now most gun-control laws, including the Brady bill requiring registration, have exempted police. They are, after all, trained law-enforcement officers. Police unions argue that under the new law civilians can still go about their jobs even if they must give up their guns. “It is patently unfair to police officers,” said Beth Weaver, a spokeswoman for the National Association of Police Organizations. Still, supporters reasonably argue that cops especially need to be held to a high standard. As The Denver Post editorialized, “Police officers who are guilty of domestic violence should lose the right to practice in a profession where the ability to make cool and clear decisions… is absolutely critical.”

Opponents also attack the law’s retroactive reach. Some police-union lawyers say it may violate the Constitution’s prohibition against ex post facto laws–in this case, increasing the punishment for a crime committed before the new law was passed. It also allows no room for changed behavior. In Minneapolis, two of the cops now on leave were convicted of misdemeanors more than a decade ago. And, according to their union, the offenses involved shouting matches, not physical violence. All four cops (who weren’t identified) disclosed the misdemeanors on their own. Chief Olson, while supporting the law, says it needs to be sympathetic to someone “who, 20 years ago, made a mistake.”

Such comments may sound distressingly familiar to domestic-abuse counselors, but they may yet get a sympathetic hearing in Congress. Several House members suggested that the Clinton administration misinterpreted the retroactivity provision, and are calling for making the law apply only to new cases of domestic abuse. The administration, however, is opposed to any changes, fearing it would remove any teeth and allow all past abusers–not just cops–free to own a gun. Given the new importance placed on reducing domestic violence, that’s a risk it would rather not take.