AFTER THREE unsuccesful attempts, the Senate has finally voted to shut off a filibuster that was a nostalgia trip to the '50s. The issue was the one that used to tie the Senate in parliamentary knots for weeks: state's rights versus civil rights. But the rules are different now (only 60 votes are needed to close debate), and far fewer people are engaged in the conflict.

The filibuster was aimed at killing a bill permitting the attorney general to bring lawsuits on behalf of inmates who are being abused in state hospitals, jails and juvenile institutions. It is, in considerable part, merely a housekeeping measure. The Justice Department already gets involved in many of these cases once inmates file suit themselves. But that fact has been overshadowed, as have many of the arguments for the bill (inmates do not make good lobbyists), by the violent opposition that has appeared.

What is the problem? The proposal, according to Sen. Strom Thurmond, is "one of the most dangerous bills that has come before Congress in the 26 years I have been a member." According to Sen. J. James Exxon, its effect would be to "place the bureaucracy of the Justice Department on the backs" elected and appointed state officials everywhere. And so on.

These men, and the bill's other opponents, are indulging in overkill. In fact, all the poor bill does is let the attorney general file suit on behalf of inmates after he has discovered that an institution has a "pattern or practice" of subjecting inmates to "egregious or flagrant" conditions that deprive them of their legal rights. And he can bring such a case only after he has warned the state that the charge is imminent and has explained to state officials what changes he thinks are necessary in the way the inmates are treated and has tried to resolve the matter informally.

Those conditions were added to the bill to mollify some senators and state attorneys general who claim to believe the federal has no business watching out for the rights of people who are confined in state prisons and hospitals. But that is the proper business of the federal government. Even inmates in such places have federal rights, and the history of recent years if replete with shameful stories of how much inmates have had their rights stripped away.

This is a pure civil-rights struggle, the genuine article, and one of the few in the present session of Congress. Now that the filibuster has been broken, the Senate should pass the bill quickly.