Back to campaign spending limits and non- limits: We should not have said yesterday that contributions to independent political action committees are unlimited. The Supreme Court's decision this week did not affect those restrictions, and they remain, at least formally, in force. We should have said that those restrictions are irrelevant, since the law now limits neither individuals nor the political action committees in the amounts that they can spend independently of -- but in support of -- a candidate's campaign.

CONGRESS' attempts to limit political spending are not holding up well under court review. The rules are steadily getting more complicated, more contorted and less useful. With the Supreme Court's decision this week, Congress now needs to decide whether the basic idea of spending limits is worth trying to save at all.

Probably not. Congress correctly sees this flood of money as attempts to buy influence. But the courts see it, also correctly, as political expression protected by the First Amendment. In 1976, the Supreme Court held it unconstitutional to limit a person's spending on his own candidacy -- which is very nice for wealthy candidates -- or on independent efforts in behalf of another person. Direct contributions to other people's campaigns remain limited by the law.

But if the Constitution permits one rich person to spend whatever he pleases to promote his political views, how about a group of not-necessarily- rich people running a joint effort? That's the question that the Supreme Court answered this week. The joint effort is the National Conservative Political Action Committee, which deliberately broke the law last year by spending vastly more than the $1,000 limit to support President Reagan. But, the court says, the law is unconstitutional.

In a dissent, Justice White objects that the Constitution protects free speech, not free spending. But Justice Rehnquist, writing for the majority, argues that restricting spending to $1,000 in a national election "is much like allowing a speaker in a public hall to express his views while denying him the use of an amplifying system." That's right, and if it's true for an individual it must also be true for a committee -- NCPAC.

The court thinks that unlimited contributions made directly to a candidate's campaign raise a threat of corruption, but unlimited contributions to independent expressions of opinion do not. What's the definition of independence? The court speaks of "the absence of prearrangement and coordination" with the candidate's campaign. The Constitution permits restrictions on political giving by corporations, the court says, but not by free associations of individuals.

The political effect of this decision will be to weaken further the two parties in relation to the special-interest advocacy organizations. Contributions to the parties will remain limited, while contributions to the independent committees will not. That can't be what Congress had in mind. The simplest and best response is to abandon altogether the limits on campaign spending by individuals and to rely on public disclosure of contributions to discipline the campaigns. The court has already upheld the disclosure requirements, and voters are entitled to know who's bankrolling whom.