THE SUPREME COURT seems on its way to becoming the biggest federal deregulator of them all. For several years it has been steadily taking power from the federal courts and giving it to state courts. The justices did it again this week in a decision that comes close to telling the federal lower court judges to ignore unconstitutional conduct by state courts in all but the most flagrant cases.

Ten years ago, before the Burger court got its hands on the law, federal judges often entertained complaints by citizens who claimed their federally guaranteed rights were being violated by state courts or state legislatures. Understandably, the state judges didn't care for this, especially since the federal courts sometimes found the complaints to be valid.

Taking heed of the states' grievances and its own sense of what the proper distribution of power between state and federal courts should be, the Burger court began to curtail federal power in 1971. Its latest move came in child-abuse case from Texas. The parents has turned to a federal court for help after their children were held in custody for more than three weeks without a judicial hearing having been conducted or even scheduled. The three federal judges who listened to their plea ruled unconstitutional the Texas law permitting such a situation to arise. But they were told by the Supreme Court last Monday that they shouldn't have bothered. Because the parents could have challenged the state law in the state courts, a majority of five justices said, the federal court should have "abstained" from correcting the situation.

Now that may make sense as a logical, flow-chart kind of division of work between the state and federal courts; the federal courts give the states a chance to correct their own errors and only move in when they fail to do so. What could be more managerially sound? But except in terms of judicial theory this provides much protection of a person's federal constitutional rights. Few state courts systems are as sensitive as federal courts to those rights - and even fewer state trial judges than federal judges think about them at all.

Behind the refusal of the court to let federal judges exercise power that is conceded to be theirs in circumstances like that in the Texas case, is the belief that abstention will, eventually, improve the quality of state courts by forcing more important issues to be dealt with by them. But the price in individual rights is likely to be high. It is one thing to urge states to correct their own bad practice - but quite another to tell parents that the courts to which they must turn when their rights have been ignored are the courts that have done the ignoring.