UNLESS YOU are writing a PhD thesis about the public papers of former president Richard Nixon or have been an active participant in the litigation itself, you have probably not been following the various court decisions concerning ownership of and access to his papers. Maybe you even thought the whole thing had been settled when, in 1974, the Supreme Court ordered the chief executive to produce certain tapes and documents that had been subpoenaed during the Watergate crisis. Or, you may have assumed it was all over when these tapes were made available to the general public in the National Archives. If you were lulled into a false sense of finality by any or all of these events, you were probably surprised to see note in this paper of yet another Supreme Court action on the Nixon tapes. And since there's a chance there will be even more litigation ahead, you'd better catch up and get ready for the next round right now.

First, forget about all the tapes and documents that were concerned with the Watergate scandal. Concentrate on the other papers and reels generated by the president during his entire time in office. This is the material now at issue. In recent years, presidential papers have been made available to the public -- at presidential libraries, for example -- but under conditions imposed by the president himself. Thus, Lyndon Johnson removed papers that he deemed to be personal, and John Kennedy provided that certain documents not be made public for a number of years. At the time of President Nixon's resignation from office in 1974, he directed the General Services Administration to send all his papers and tapes -- 42 million pages of documents and 880 tapes -- to California so that he could go through them, make copies and, after a period of time, direct that certain tapes be destroyed.

Not so fast, said Congress--and within three months, legislation was enacted giving the GSA complete control of the papers with the right to sort them out and return those that were clearly private and of no "general historical significance." Mr. Nixon challenged the law, but it was upheld by the Supreme Court. Then he challenged the regulations promulgated by GSA that provided that archivists would listen to every tape before deciding what material was private and should be returned to the former president. Some tapes, he claimed, were clearly labeled diary entries and should remain confidential.

Not a chance, said the district and appellate courts, and last week that opinion was made final when the Supreme Court refused to hear an appeal.

This doesn't mean that someday -- it will take the archivists three years to listen to all the tapes -- we can all go downtown and eavesdrop on conversations between the first couple about the suitability of prospective sons-in-law, or arguments about who failed to enter the $34.62 check to Sears in the joint account records. Such conversations would clearly be private and Mr. Nixon's property. But we might learn many things of interest concerning the Nixon years.

What separates Mr. Nixon from all other presidents in this respect is that the distinction between what is personal and what is public is outside his control. Under present law, which went into effect last year, presidential documents automatically become the property of the United States, but private documents -- such diaries, journals and personal notes as the president himself determines -- are excluded. In addition, a president can now keep documents from becoming public for as long as 12 years after he leaves office, which Mr. Nixon cannot do.

There will surely be more litigation as the former president challenges the archivists' decisions on certain tapes. But in these two respects -- deciding what is private and timing the release of documents -- Mr. Nixon has been treated differently from any other man who has held the nation's highest office. It's the price he has had to pay for the way he conducted the office and the utter collapse of respect that occurred between himself and Congress.