ON THURSDAY, the conference committee considering the State Department authorization bill is scheduled to take up the question of the Palestine Liberation Organization's information offices in the United States. The Senate version of the bill contains a provision that would force these offices in Washington and New York to close their doors and would prohibit anyone -- including American citizens and legal aliens -- from opening an office or spending or receiving money "at the behest of the PLO" in order to publicize its non-terrorist views. It's a terrible, small-minded idea that is clearly at odds with the First Amendment, but chances are good that both conferees and Congress will approve it.

Contrary to the claim of its sponsors, this legislation is not directed at terrorism -- every form of which is already illegal -- but at speech. The PLO is not popular in this country, and for more than good reason. But it is not criminal in this country to publish and disseminate unpopular views, to challenge decisions of the legislature and the foreign policy establishment or to criticize good friends of the United States. For 10 years, that's what the PLO information office in this city has been doing. In September, the State Department, in an apparent effort to head off this legislation, reversed its long-held view that the activities of the office were both legal and constitutionally protected; it ordered the office shut down. But that didn't satisfy senators who pushed to close the New York office, which is attached to the PLO observer post at the United Nations, as well.

The State Department's action is being challenged in U.S. district court here, and an initial ruling may be made this week. This is one of those times to be grateful for the third branch of government. The courts, unlike Congress and the executive, have been purposely isolated from the kind of pressures that lead elected and politically appointed officials to capitulate to misguided demands. It is really disgraceful that liberal senators in particular, who usually champion the First Amendment rights of the unpopular, have supported this legislation and the State Department's action. It will be up to the courts to reemphasize the distinction between illegal acts and protected speech. Everyone, even a supporter of the PLO, is entitled to join in public debate and to be heard.