SUPPOSE YOU are the sheriff of a small, rural county in south Georgia. You earn about $8,000 a year and have begun to wonder how you are going to send your kids to college. One day you are offered $50,000 to go into Joe's diner on the highway and have a cup of coffee. This is not money paid for killing someone, or for leaving a cell unlocked or even for tearing up a parking ticket. All you have to do to earn this princely sum is to sit in the diner sipping coffee and talking to your friends while a small plane lands in a cow pasture 10 miles away. If you simply don't notice the arrival of a million dollars worth of cocaine in a single-engine private plane at an isolated spot, all your financial worries will be over. Could you withstand this temptation? The Justice Department reports that with increasing frequency, small-town law enforcement officers are finding this kind of offer irresistible.

They aren't the only ones. The money involved in the illegal drug market is so substantial -- sales of $79 billion a year and profits greater than any U.S. corporation -- that large amounts of cash are available to bribe public officials at all levels of government. A leading agent in the Fort Lauderdale office of the Drug Enforcement Administration has been indicted on four criminal counts involving the smuggling of drugs and obstruction of justice. FBI Director William H. Webster has cited problems not only with DEA officials but also among FBI agents and Justice Department prosecutors as well. He predicted indictment of some of these law enforcement officers in the near future. Convictions would be a terrible blow to two agencies thought to be virtually incorruptible by organized crime.

Can anything be done to stem this bribery, without which the drug trade would collapse? Of course, it helps to start with honest public officials, and most are. But with so very much money available to buy cooperation, there will always be sellers. Mr. Webster is wise to admit to problems within the bureau and express his determination to see that the offenders are prosecuted. The Justice Department and the DEA, to their credit, moved quickly to build an impressive case against the Florida agent. It is important not only that these cases be brought and won, but that they also be given maximum publicity. Prosecutions reinforce the ethical standards of those officers who cannot be bribed and, at the same time, serve as a warning to those who are tempted that they will be sought out.