It is not surprising to hear a law enforcement official, in this case Montgomery County Police Lt. Ronald Ricucci, head of the narcotics unit, resort to the tired, old end-justifies-the-means argument to support questionable tactics being used to fight the scurrilous street trade in drugs.

What is disturbing, however, is to see the top county prosecutor, Andrew L. Sonner, ignore his schooling in the finer points of constitutional law and jump on the police bandwagon, or paddy wagon as the case may be {"Montgomery's New Tactics in War on Drugs," Metro, June 28}.

Lt. Ricucci concludes, and Mr. Sonner seems to agree, that a 90-percent conviction rate in court validates the "jump-out" system whereby deep suspicion and circumstance combine in the police mind to create probable cause for an arrest and search. What neither man is willing to say, however, is that 90 percent of only those eventually arrested are convicted. How many innocent drivers, passengers and standers-by are never arrested after being put through the dangerous ritual of armed manhandling and warrantless searches of their vehicles and persons? What percentage of the county's innocent population must be subjected to verbal and physical abuse, and infringement of Fourth Amendment protections, before police finally come up with the goods and make an arrest?

What every lawyer knows, and what prosecutor Sonner conveniently overlooks, is that a warrantless search based on suspicion, not founded in probable cause, cannot be justified by the contraband it may discover. Illegal at its inception, the search remains illegal and cannot be excused by the fact that the suspect might later be convicted. Mere suspicions are easily embellished when the search happens to turn out "successful." Despite our TV-induced perceptions, few are the judges who will throw out the evidentiary fruits because of the proverbial technicality.

The losers in this constitutional game are not the drug dealers. The losers are you and me, everyday people who take some comfort in the knowledge that the Fourth Amendment was designed to prevent the very police-state tactics in question. The criminal justice system and government as a whole lose respect in the eyes of citizens wrongly detained and searched. Don't protest too loudly, though, or you'll probably get locked up for disorderly conduct. CARY CLENNON Washington