THE BILL passed by the Senate the other day to establish a mechanism for disciplining federal judges is the best that has been proposed in 30 years of talk about the subject. But it still has a problem: it may -- or may not -- be constitutional.

The bill directs the nation's 11 judicial councils to entertain complaints from citizens who believe particular fededral judges are mentally or physically disabled or have engaged in conduct inconsistent with the effective administration of justice. The councils, composed of other federal judges, may dismiss the complaints, certify a judge as disabled, ask the judge to retire, direct that cases not be assigned to him, issue private or public reprimands or recommend impeachment. These decisions would be appealable to a Court on Judicial Conduct and Disability appointed by the Chief Justice.

The arrangement is designed to provide, for the first time, a system other than the tedious and rarely used impeachment process by which federal judges can be called to account for their non-judicial behavior. And therein lies the problem. Sens. Charles Mathias of Maryland and Howell Heflin of Alabama argued passionately that Congress has no power over the conduct of judges except the impeachment power.

It comes down to a question of whether the imposition by Congress of idsciplinary measures administered solely by other judges infringes on the dependence of federal judges. That is a hard question, and one the House should consider carefully as it takes up the bill. The system of discipline proposed the Senate is similar to a system the judges themselves are now inaugurating. It is far less severe than a bill approved by the Senate a year ago to permit the removal of judges in some situations without impeachment. Yet, does the Constitution permit Congress to take even this limited step into the internal affairs of another branch of government?

It is rare for Congress to focus directly on basic constitutional questions; those are usually left to the courts. But in this case, that kind of scrutiny is required. The answer to a question about judicial independence should come from Congress and the president, not from the judges themselves.