WHAT SHOULD BE done about political action committees that make "independent expenditures"? Such PACs raise money, entirely legally, and then spend it on advertisements for or sometimes against political candidates. The Supreme Court has ruled that the First Amendment prohibits the federal government from barring such spending in congressional elections, unless there is contact or collusion with the candidate in whose behalf the money is spent.

So much is clear. Now comes the question of the legality of "independent expenditures" in behalf of presidential candidates who accept public financing. The Supreme Court deadlocked, 4-4, on the issue last year. Those who would make such expenditures illegal argue that the law prohibiting any such spending over $1,000 is a reasonable way to make the public financing system work and to ensure equal competition between the parties.

Taking the opposite view are the National Conservative Political Action Committee and the Fund for a Conservative Majority. They say they plan to spend some $10 million to reelect President Reagan. Why should government be able to limit their freedom of expression, they ask, just because the candidate, whose cause they want to advance, has accepted (or may accept) some federal money?

NCPAC and FCM are hopping mad because the Federal Election Commission has announced it will enforce the law against such expenditures. They argue that unless they get a speedy decision in court, they may be barred from making what may turn out to be entirely legal campaign expenditures. But the FEC has a good argument too: it is probably obliged to enforce a law that has not been definitively declared unconstitutional.

As a practical matter, some $13 million was spent independently in the 1980 presidential campaign, mostly for Mr. Reagan, and similar sums will likely be spent in 1984 if the courts allow the practice--unless the FEC cracks down and requires independent expenditures to be really independent. There's the nut of it. It's not easy, in the world of political consultants and operatives, to spend such large sums without some contact or collusion. Supposedly independent spenders and the leaders and staffers of the campaigns they aid have webs of business relationships, political alliances and personal friendships that go back for years.

The FEC could considerably reduce such spending, in presidential and congressional races, by announcing an aggressive enforcement program--monitoring campaigns and PACs closely to detect any contact or collusion and seeking stiff penalties for violations.