ANYONE WHO LIVED through the series of demonstrations that rocked Washington between 1969 and 1971 has his own perception of what happened. But those individual perceptions differ, and it is still possible to get into bitter arguments as to who behaved worse - the demonstrators or the police. If you weren't here, and would like to read two dramatically contradictory views based on precisely the same evidence, we recommend to you a decision of the U.S. Court of Appeals this week and the decision that it overturned - that of District Judge Joseph C. Waddy. According to Judge Waddy, who heard many days of testimony, the Metropolitan Police Department did practically nothing right during those demonstrations. But according to the opinion written by Circuit Judge Roger Robb, after reviewing that testimony, the police did practically nothing wrong.

Our perception is different from both. We thouhgt then - and think now - that the police generally handled difficult and unprecedented situations in a commendable way. But we also thought then - and think now - that there were many episodes in which the rights of demonstrators were not honored (to put it mildly), that some of these were due to faulty judgment by ranking police officials and that some of the abuses of police power were indefensible.

So we are just as disturbed by the opinion of Judge Robb as we were 18 months ago by the opinion of Judge Waddy. Judge Waddy looked at the demonstrations from a narrow perspective and generalized about the nature of police conduct as a whole from the few specific incidents he picked out. Judge Robb has done it the other way around. By looking only at the general scene and avoiding particulars, he can absolve the police of any misconduct. It is a remarkable demonstration of how biases or individual perceptions can get in the way of fact finding, even among judges.

Although we were critical of Judge Waddy's opinion when it was issued, we had no real reservations about the things he ordered the police department and the city government to do. He directed that a handbook be prepared on how officers should react during mass demonstrations. He barred the use, in political demonstrations, of the city's ordinance authorizing the establishment of police lines to clear certain areas until reasonable limitations on its use were approved. He ordered the police not to make arrests unless they are prepared to document to the reasons for them. And he told the department to be generous in clearing the records of those who were arrested without probable cause during the demonstrations.

Those seemed us to be steps that the city should take - with or without a judicial directive to take them. And we think it is unfortunate that the Court of Appeals has overturned all of them except the one concerned with police records. This city may never again be faced with a wave of demonstrations like those at the turn of the decade. But there are useful lessons to be learned about what was done right and what was done wrong. It is not particularly helpful to have the Court of Appeals obliterate those lessons.