THE HATCH ACT -- its official title was An Act to Prevent Pernicious Political Activities -- was passed in 1939 in part on the sneaking suspicion that Democrats were using public-sector jobs in that Depression era not just to restore prosperity but to lock up the future good fortune of their party as well. The act thus began by prohibiting political coercion or solicitation of federal employees, but the authors were not content with that. They also barred civil servants from most participation in political campaigns.

There have been repeated efforts to amend this latter ban, mostly on familiar First Amendment grounds. In the 1960s a commission said its provisions should be relaxed, and several lower federal courts also found against them. But in 1973 the Supreme Court upheld them. Congress then passed a bill in 1976 repealing much of the original legislation, but President Ford successfully vetoed it.

Now a new effort has begun. Rep. William Clay has introduced basically the same bill that passed 11 years ago. The coercion and solicitation sections of the original law would, if anything, be strengthened. But most federal and postal employees would be free when away from work to take full part in political campaigns; they could even have leave without pay to run for office themselves. The law would treat them like -- gulp! -- grown-ups.

The step is long overdue. The First Amendment is the primary reason, of course. But the ridiculousness of the regulations to which the enforcers of this law have been reduced is not far behind. As a compromise with free speech, for example, the regulators have generously decided that, yes, a federal employee should be able to put a campaign sign in his front yard. But government being what it is, the questions quickly follow: What kind of sign? How large? Surely not a billboard. The regulatory office has finally settled on 14 by 22 inches or less for a front-yard sign, somewhat different dimensions for a sign on the family automobile . . . and on and on and on.

The administration is against the pending bill on grounds that the present system is already a fair balance between the right to free expression and the need to insulate the federal work force. But House Republicans are trying to work with the sponsoring Democrats on a compromise. Rep. Pat Schroeder said in the debate in 1975 that the Hatch Act was passed "in order to protect federal employees from politicians. It has been retained in order to protect the politicians from federal employees." That may not be entirely true, but it's true enough to make the case. This suspect law should be revised.