The West German Parliament is about to enact an extraordinary legal measure for a democratic society - a law that would isolate jailed terrorists from their lawyers during "emergency" periods.

West German authorities have been convinced for some time that some of the attorneys are fuctioning as a communications link that contributes to the terrorism.

The abduction of industrialist Hanns-Martin Schleyer in Cologne on Sept. 5, and the peculiar events leading up to it, have now provided enough pressure for Parliament to take legal steps to break the link.

Four days before terrorists in five different West German prisons abruptly and simultaneously ended a hunger strike that had been going on for almost a month.

At the time, the prisoners' decision seemed peculiar because they failed to extract any concessions from the Bonn government over their complaints of allegedly poor prison conditions.

In the aftermath of the Schleyer kidnaping, however, West German security authorities are convinced that the jailed terrorists had been tipped off about the impending kidnaping and were trying to restore their strength for the eventual demand by the kidnapers for the release of 11 jailed terrorists in exchange for Schleyer.

The police also believe that at the heart of the sophisticated communications system that appears to link the prisoners with the outside world are the radical lawyers who carry messages and plans in and out of the prisons.

The new bill is moving through Parliament in minimum time of three days and was introduced with the support of all major government and opposition parties. It would basically isolate jailed urban guerrillas from all contact with the outside world.

This includes a ban on visits by lawyers or relatives, the authority even stopping their access to radios and newspapers.

The law is meant to be applied in emergency situations and for a limited period - probably 30 days - although the time could be extended. It also applies only to persons convicted of terrorist cimes and not to other criminals.

The new law comes in the aftermath of a wave of terrorist murders and kidnappings over the past five months by the extreme leftist Red Army faction. The incidents have shaken up West German society, produced opposition demands even stricter new laws and reinforcement of police, and put pressure on the government to take some action in the absence of any success thus far in tracking down terrorists still at large.

Actually, West German authorities clamped a ban on visits to the jailed terrorists immediately after the Schleyer kidnaping and the new bill basically is meant to make that ban permanent.

Lawyers for some of the prisoners have challenged the intial ban in the courts. Recent reports indicate, however, that the West German Supreme Court has already decided that the police action was legal given the gravity of the terrorist challenge. A full test of the GAN's constitutionality will presumably be made at some time in the future. The West German constilution is generally viewed as highly liberal in terms of protecting individual rights but it is unclear on the definition of the kind of emergency that would make new laws necessary.

The dimensions of West Germany's difficulties with the hard core of about a dozen attorneys specializing in representing extreme lefist terrorists is relfected in Justice Ministry stastistics that show almost 13,000 visits to 12 jailed terrorists over a two-year appeared period by lawyers who brought some 60,000 prices of mail.

One lawyer, Siegfried Haag, 32, is now in jail awaiting trial on charges of masterminding the 1975 attack on the West German embassy in Stockholm. Another long-time prayer for the Baader-Meinhof terrorist gang, the Badder-Meinhof terrorist gang, Klaus Croissani, 47, is wanted here on similar chnarges. Croissant fled to France in July.

Aside from the new bill, the Justice Ministry has also said the government is considering other Legislation that would allow courts to debar lawyers who are suspected lawyers who are suspected of conspiracy with their defendants in terrorist cases.

That appears to be as far as the left-center coalition government of Chancellor Helmut Schmidt is prepared to go in terms of new legal restrictions. When the Schleyer case is over and public and political frustrations calm down, however, it may be that even this proposal will not make it through Parliament.

Chancellor Schmidt, has warned that West Germany will not play into the hands of th terrorists by over-reacting and passing laws that infring upon indivdual liberties.

But oppsition Christian Democrat leader Helmut Kohl has alread told party audiences that West Germany must be prepared if necessary to amend the constitution in reas where it provides the terroists lawyer swith opportunites to undermine legal order.

A call for far sterner measures also came this week sterner measures also came this week from the Christian Democrat's sister party, the even more conservative China Social Union, which operates only in the state of Bavaria.

Although many of the Christian Socialist proposals are not likely to make it through Parliament, they reflect the demand of many conservatives to get tough.

The thrust of several of them was endorsed Tuesday by the 40,000-member police trade union.

The Christian Socialist proposals include prosecution of persons publicly endorsing violence or encouraging participation in banned demonstrations. They would involve monitoring of conversations between terrorists and their attorneys, disbarment of lawyers on still narrower suspicions of terrorist sympaties and increased use of preventive detention.