If the Montgomery County police stakeout goes according to plan, Jerry Garnett Williamson and Jerry Lee Atkins will never know what hit them.

As their silver sedan rolls slowly to a crowded basketball court at the Summit Hills apartment complex in Silver Spring, they are unaware that a plainclothes officer is secretly watching the area, where police believe a juvenile drug seller is doing business while shooting hoops.

When Williamson, a 29-year-old Rockville man, gets out of the car and walks to the suspected dealer, his movements are radioed to five officers waiting for just this moment in unmarked cars at the edges of the sprawling housing complex on East-West Highway.

Strapping guns to their waists and firing up their engines, the undercover police wait for word that money and a tinfoil wrapper have changed hands. Then they strike.

In moments, Montgomery County's jump-out squad will roar up to the court, leap from their cars and arrest three people: the suspected dealer, who was not identified because of his age; Williamson, and Atkins, who has never left the car or gotten close to the foil wrapper and is not directly involved in the transaction. With about 20 basketball players watching impassively, the three are handcuffed and charged with possession of $8 worth of marijuana and the hallucinogen PCP.

The suspects are now awaiting trial, and Atkins' lawyer, Atiq Ahmed, said his client is innocent. The public defender's office, which is representing Williamson, has not determined what plea it will enter in his case.

The arrests, which occurred May 21, illustrate what supporters praise -- but what critics deplore -- about Montgomery's nine-month-old "jump-out" squad, the antidrug force inspired by the District's highly publicized Operation Clean Sweep.

Since it began targeting small-time drug buyers and dealers in September, police and some community leaders say, the six-member squad has helped clean up neighborhood drug problems that are beyond the reach of traditional police methods. Also, the squad is providing significant new leads in tracking the larger suppliers who frequently elude detection efforts, according to police and prosecutors.

But the program has provoked sharp criticism from the defense lawyers handling Montgomery's ballooning numbers of low-level drug cases. They say the jump-out officers are violating the rights of suspects by commencing arrests without being certain that what they are seeing -- often at a distance -- really is illegal drug activity.

Defense lawyers contend that the squad makes arrests without the "probable cause" needed to justify their actions legally, and they contend that innocent bystanders frequently are caught up.

They say raids are too easily initiated, based on sightings of supposedly suspicious activity -- such as a possible suspect wiping his or her nose, or two people sharing a cigarette. While these actions could suggest drug use, they could just as easily be innocent, the lawyers say.

Also, the lawyers criticize the practice in which the police automatically confiscate automobiles of drug users, no matter how small the drug activity they are allegedly involved in.

"I call it the jump-to-conclusion squad," said Reginald W. Bours III, a Rockville lawyer. "They've done more damage to the Fourth Amendment than the residents of Montgomery County can possibly imagine," he said, referring to the constitutional provision limiting searches and seizures.

But police Lt. Ronald Ricucci, who heads Montgomery County's narcotics units, dismissed the lawyers' complaints "as just sour grapes. We have a conviction rate of over 90 percent, and that speaks for itself."

The jump-out squad was formed as a pilot program in September and was made permanent in November. Like its D.C. counterpart, Operation Clean Sweep, it focuses on small-time users, trying to break up the street drug markets that have held some neighborhoods increasingly hostage.

In a Nov. 26 news conference, Police Chief Bernard D. Crooke and State's Attorney Andrew L. Sonner announced the central elements of the program. Low-level users would be arrested, those driving cars when they were arrested would have their vehicles confiscated in order to provide swift punishment, and those convicted would be called before a grand jury to testify about their drug connections.

The goal was to hurt drug suppliers indirectly, by raising the potential costs for drug purchasers.

"Users can't believe what they're going through," Ricucci said. "It doesn't matter if it's a joint or an ounce, we treat them all the same."

Since its inception, the jump-out squad has arrested 349 purchasers and sellers, seized 57 vehicles and confiscated $18,601 in cash and $18,789 worth of drugs, Ricucci said. Of the cases that have reached court, 91 percent have led to convictions, he said.

Although the majority of first-time offenders receive probation but no jail time, Crooke said the program has sent a strong message. "We want to set up an atmosphere where if you do use, you've got a reasonable chance of being arrested."

Major targets of the squad have been along the Rockville Pike restaurant and bar corridor. Ricucci said the unit also has visibly reduced drug activity in Rockville's Lincoln Park area, along Scenery Drive in Germantown, and in Emory Grove, on Rte. 124 between Gaithersburg and Laytonsville.

On June 18, the squad mounted its biggest operation to date. Based on neighborhood complaints and covert surveillance, the squad raided four Wheaton homes in the Connecticut Avenue Estates area, arrested 17 people, and seized cocaine, crack and PCP.

"That's what jump-out's all about," Ricucci said. "We're going into these areas and getting tremendous cooperation from the community. I have never seen so much support for a program."

Ardell Shirley, president of the Lincoln Park Civic Association, said the squad has had a positive, if temporary, effect on street drug sales. "I couldn't believe how clean the streets were" after the first arrests in February, Shirley said. But since then, she and other residents said, drug sellers have returned, sometimes within a week.

Crooke acknowledged that the effect is sometimes only temporary, but he predicted that the squad will put more consistent pressure on drug sellers in December, when the unit increases from six to 10 officers. "That will go a long way to helping us keep the neighborhoods clean."

Crooke and Sonner praise another result of the jump-out effort: the funneling of witnesses to the county grand jury, where they can be interrogated about alleged drug suppliers. Sonner said that more than 200 witnesses have been brought before the grand jury after their arrests.

"We are finding out information we never even dreamed of getting," Sonner said. People who are named in grand jury proceedings as dealers are being brought before the panel themselves and asked about their suppliers.

The testimony, Sonner said, is enabling police to trace bigger drug networks through surveillance and the logging of telephone numbers dialed by dealers. Said Sonner: "We're going to try to take the higher-ups, too."

While law enforcement officials sing its praises, critics such as Hyattsville lawyer Victor Houlon question the benefits of the jump-out squad.

"If you and I were in a car in one of these problem areas and down to one cigarette, if they see you passing it, the following will automatically happen: They will run up to both sides of your car, with no uniforms or badge. They will pull the doors open and physically drag you out of your car and search every corner of it," Houlon said.

"Treating you that way and treating your privacy that way is wrong," he said. "It gets down to the old business of what this country is about."

Rockville lawyer Bours said police, particularly in night operations, begin their arrests without seeing drugs.

"In my humble opinion, it's not probable cause" to make an arrest, Bours said. "What they've done is make a pretty good guess, and you don't get any credit for good guesses in Fourth Amendment law."

Sonner said the ability to make legal arrests based on suspicious motions hinges on the training of the officers. "The bottom line is that we're not losing these cases. That tells me they're making good arrests and using good judgment."

In some cases, though, even careful surveillance by police yields only ambiguous evidence. In the May 21 arrest at Summit Hills, Williamson got out of the car, approached the suspected dealer, and then returned to his car, where Atkins, a 28-year-old Suitland man, passed some money to him, police said.

Following their arrests, Williamson and Atkins were taken to the Silver Spring station. There, in separate interrogation rooms, they told police an identical story: that Atkins was receiving a ride home from Williamson and had no idea Williamson planned to stop at Summit Hills.

Williamson told police that he returned to the car to borrow 50 cents from Atkins.

Although he was not in direct contact with the alleged dealer, Atkins was charged with two drug counts.

Sonner said that in such ambiguous cases, perceptions of a defendant's character and credibility can play as great a role as the physical evidence. "If he doesn't have a record, the judge will usually find him not guilty. If he has a record, they'll usually find him guilty . . . . It's probably a case we'd take to trial."

Atkins and Williamson are scheduled for District Court trials in July.

Even where there is a clear sighting of evidence, some critics question whether the tactic of making surprise arrests for small amounts of drugs is worth the risk.

About 5 p.m. on Jan. 13, for instance, what began as a routine jump-out arrest at a Wheaton shopping center rapidly escalated. As police were about to make an arrest, William Roy Crews II, 26, of Rockville leaped into his car and backed up toward an approaching officer, police said.

Officers fired nine shots at the car as it drove into the intersection of Veirs Mill and Randolph roads at rush hour. Crews, who awaits trial on charges of drug possession and assault in an attempt to flee arrest, was later arrested with 3 1/2 grams of PCP-laced vegetable matter, according to court records.

"The case just exemplifies the problem. The risk for the return is so great that it's just ridiculous," said Crews' attorney, Philip H. Armstrong of Rockville. "Three bullets went through the rear window. It's a miracle nobody was hurt."

Ricucci said the gunshots were investigated and found to be warranted by the police department's internal affairs office. "It was a proper use of force," he said, adding, "There's always a risk with every police action. Actually, we've been surprised by how few problems there have been."