If you are one of the 527,000 young men over age 18 who have failed to register for the draft, you may be wondering when the federal government is going to come after you. After all, failure to register is a felony punishable by five years in jail, and although President Reagan, in deference to his own opposition to draft registration as a candidate, did not enforce the law in 1981, he did announce clearly his intention to do so this year. Young men were given until Feb. 28 to register; the publicity attendant upon this extension should have made it unmistakably clear that those who failed to register risk prosecution.

Or do they? Excerpts from the transcript of an April 12 meeting of the president's Military Manpower Training Force, published in this newspaper last week, show more caution than eagerness to enforce the law. An assistant secretary of the Navy wants to proceed cautiously because "felony prosecutions at this time may have an awful lot to do with the anti-nuclear movement." The secretary of defense wants to keep court cases out of the District of Columbia. The director of Selective Service speculates on whether milder sentences than the maximum can be given (they can) and states (incorrectly) that "there can't be selective prosecution."

The administration's trepidation may turn out to be well-founded. Nevertheless, it's time that the government get down to the business of enforcing the law. That does not demand that every single violator be prosecuted, but the government must show it is serious. As with prosecutions under the tax laws, the government must encourage voluntary compliance and also show those who do not comply that flagrant violators will be punished appropriately. There is nothing wrong with targeting for prosecution those who have urged defiance of this law. Nor is there anything wrong with bringing prosecutions in courts where the chances of conviction are high and the chances of distracting demonstrations are low. Prosecution must begin somewhere, and those who--for reasons of conscience or just convenience--have deliberately violated the law have no legal or moral standing to question why it should begin with them.

The Reagan administration should be criticized, not for planning to make its prosecutions successful, but for not bringing them sooner. Only 225 people have been referred by Selective Service to the Department of Justice for prosecution; no prosecutions have been brought. Congress, by passing the registration law, has already decided that society has a legitimate claim on as much of its young male citizens' time as it takes to register; the president, by his announced determination to enforce the law, has rejected the argument that this law is no more enforceable than Prohibition. Young men who may be wondering whether it is a good idea, after all, to register should get a message from the government--soon.