Twenty-six states have already passed "shield" laws to protect the press from being compelled to reveal confidential sources of information. Other states are moving in the same direction. so is Congress, where a similar federal statute is in the making.

There is no mystery about this, for the lawmakers are simply responding to a growing trend among judges - local and state as well as federal - to curb the rights of the press, especially those claimed under the First Amendment. There has been a veritable explosion of litigation with the basic issue being how to reconcile the constitutional rights of the press with the rights of individuals.

The rapid growth of the shield laws reflects the judgment of legislators that, in practice, the threat to individuals has been more hypothetical than real in cases involving the confidentiality of news sources. Few actual cases can be cited where preserving confidentiality has seriously impaired or obstructed justice.

There is nothing theoretical, however, about the impressive services the press has been able to render the public through exposes that could not have succeeded without the protection of confidential sources. That was as true of the Teapot Dome scandal almost 60 years ago as it was of Watergate - plus thousands of other investigations of official corruption in between.

Current interest in the problem has been inspired by the action of New Jersey Judge William Arnold in citing The New York Times and one of its reporters, Myron Farber, for contempt in refusing to turn over unspecified notes and materials subpoenaed by defense attorneys in a murder trial.

The trial is the aftermath of Farber's 1975 investigation of 13 suspicious deaths in a New Jersey hospital in the 1960s. His meticulous reporting was partly responsible for reopening of the case, which in turn led to the indictment of Dr. Mario Jascalevich, who is now on trial for three of those deaths.

In challenging the subpoena, The Times and Farber relied not only on the First Amendment, but also on the New Jersey shield law, supposed to be the strongest in the United States in protecting confidential news sources. The Times further argued that the subpoena was so sweeping and imprecise as to be little more than a fishing expedition.

The judge brushed aside the shield laws and rejected a plea for a hearing on the merits of the subpoena as well. His order was to bring in everything and he would decide privately what, if anything, was relevant to the trial. His order is being appealed, but meanwhile The Times has been fined $100,000, plus $5,000 a day, for non-compliance, and Farber is behind bars for who knows how long. The state senator who sponsored New Jersey's shield law called the imprisonment of Farber a "disgraceful" act that put into "grave danger" the public's right to know through a free press.

Congress got interested in this issue in 1972 when the Supreme Court ruled that the First Amendment does not allow reporters to refuse to tell grand juries the identity of their news sources. Justice Potter Stewart, dissenting, said: "The court invites state and federal authorities to undermine the historic independence of the press by attempting to annex the journalistic profession as an investigation arm of government."

Yet, since that opinion, a dozen or more newspapermen have been jailed for refusing to disclose sources, and many more have been cited for contempt. That's why 34 national shield bills have been introduced in Congress, although none has yet become law.

Additional federal legislation has also just been proposed to nullify a recent Supreme Court decision allowing police to obtain warrants and search newspaper offices and files without showing evidence of any illegal activity by the newspapers or their employees.

Critics of the Farber case note that the Supreme Court would not let even an incumbent president - Richard Nixon - refuse a subpoena for his White House tapes. In that instance, however, the Watergate special prosecutor's subpoenas specified exactly what tapes were needed and why. In contrast, the New Jersey judge is enforcing a shotgun subpoena that appears to have no particularity at all.

Even those accused of violent crime are usually allowed their freedom pending trial or appeal, but all efforts to stay Farber's imprisonment have failed. Justice Thurgood Marshall, a liberal member of the Supreme Court, acknowledged that if he were "deciding the issue on its merits," he would have granted a stay, but he doubted that enough justices (four are needed) would grant a review. He may well be right, but suppose he has guessed wrong. If The Times and Farber are ultimately vindicated, the paper can recover its fine, but the damage to the reporter is irreparable.