ALFRED S. REGNERY, the man nominated by President Reagan to head the Federal Office of Juvenile Justice and Delinquency Prevention, is the father of four children and the owner of a car that sports a bumper sticker asking "Have you slugged your kid today?" The nominee says his children bought the sign for him as a joke, and that everyone in his family, at least, thinks it's terribly funny. The people on Capitol Hill concerned with his confirmation are not amused.

At issue in the Senate confirmation hearings, however, is the more fundamental question of the direction of the federal juvenile justice program. The office for which Mr. Regnery has been nominated was established by Congress in l974. The purpose of the legislation was to mount a federal effort to prevent crime by reaching children before they became offenders, by supporting research into the causes of delinquency, by trying to save juvenile offenders from becoming adult criminals and by sponsoring imaginative programs of rehabilitation outside correctional institutions.

Drafters of the legislation were, in fact, so certain that this program would reduce the number of youngsters confined in institutions that they added a provision designed to minimize employment problems for corrections personnel who would surely lose their jobs when juvenile institutions closed down.

The law speaks of prevention, rehabilitation, research, training, assistance, alternatives to institutionalization and improvement of the standards of criminal justice. Nowhere in the statute is there a directive to focus on punishment or incarceration. But in his recent testimony before the Senate Judiciary Committee and in press interviews, Mr. Regnery has stated that he has little faith in the value of prevention programs and wants to concentrate on apprehension and punishment of youngsters who are already offenders. Certainly it is within his power to review the recent work of the office and to make judgments about research and other projects that have been funded under the act. No individual grant recipient has a permanent right to government financing--as many affiliated with other federal programs have learned during the recent budget cutbacks. But the director's clear responsibility is to carry out the law as it is written, not as he would have written it. It is cynical to put millions of dollars into a program stressing tougher penalties for youthful offenders and then call it prevention, as the nominee did, because a youngster in jail is prevented from committing other crimes.

There are any number of crime control and law enforcement organizations at state, local and federal levels who have responsibility for juvenile corrections programs. The problem is not a small one, but neither is it the one assigned to the Office of Juvenile Justice. It is now Mr. Regnery's task to assure senators that he understands and supports the goals set out by the drafters of the law and that he intends to carry it out fairly and effectively. And it wouldn't hurt to peel off that bumper sticker as well.