EMBEZZLING MONEY from a national bank is a federal crime, but whether the embezzler gets prosecuted for it or not depends upon how much money was taken and where the bank is located. In some parts of the country, the federal government will prosecute the case only if $5,000 or more was involved. In other places, $500 is enough.

That's one of the findings in a new Department of Justice survey of how U.S. attorneys use the discretion the law gives them. There are others. Some federal prosecutors are interested in marijuana cases only if more than 1,000 pounds of it are involved; others get interested when a few pounds are seized. It takes a theft of more than $5,000 from an interstate shipment to rouse the feds in 10 jurisdictions but only $1,000 in others.

This doesn't mean that people who commit those crimes and get caught necessarily go free. Most of the cases ignored by the U.S. attorneys because they are small can be handled in state courts. But it does mean the Department of Justice is dispensing something less than evenhanded treatment to the nation's criminals.

Prosecutors, no doubt, must have some discretion about which cases to handle and which to ignore. The seriousness of the crime, the size of their staffs, the ability of state officials to handle the cases, and the age and history of suspects are all relevant considerations in the judgment of how that discretion is to be exercised. But a federal crime, big or small, is still a federal crime. The Department of Justice (or Congress, if need be: the U.S. attorneys have considerable independence) should establish better guidelines than now exist for calling federal law into action.

There may be better criteria than those the U.S. attorneys have been using. Why should the federal government be prosecuting any theft, embezzlement or drug cases that can be handled by state or local officials except when those officials are corrupt or incompetent or when the case spreads across jurisdictional lines in ways that make local prosecution difficult?

If those were the standards for federal prosecution (although not federal investigation), the public would be reminded constantly that law enforcement is a state and local responsibility. The public could also get a clear indication of the respect federal officials have for local law-enforcement personnel by the activity or lack of it in federal courts. In this day of concern about the concentration of power in the federal government, it's an idea worth thinking about.