Twenty-five minutes into the New Year, Ronald Jenkins was driving to a neighbor's party when he was stopped at a roadblock by Prince George's County police and asked to recite the alphabet.

Slowly and deliberately, the 36-year-old government worker enunciated the ABCs until he reached L. Then he shook his head and quit.

Jenkins was one of only four drivers arrested out of the 2,189 stopped by Prince George's County police New Year's morning at the sobriety checkpoint near Allentown Road and Branch Avenue, just northwest of Andrews Air Force Base. The ratio of arrests to drivers stopped is certain to fuel the growing controversy in which opponents of random roadblocks argue that not only are roadblocks ineffective against drunk driving, but also that they may be an unconstitutional invasion of privacy.

"I'm very hard on drunk drivers, but I'm not so sure we want to start stopping people randomly on the roads," said Fairfax County Police Chief Carroll D. Buracker, whose department chose not to set up roadblocks. "There is too much government intrusion already . . . and the figures show roadblocks are not the answer to drunk driving."

At the only other area roadblock reported Monday night, Maryland state police stopped 286 motorists in Harford County and arrested none. In Fairfax County, where Buracker said he opted for "saturating the streets with roving patrols" on New Year's Eve, 21 were arrested for allegedly driving while intoxicated.

Instead of a well-marked roadblock, which demands a concentrated use of manpower, District and Virginia police spokesmen said they preferred quietly staking out well-traveled routes and watching for weaving or speeding vehicles.

Prince George's County Police Capt. David Mitchell, an ardent defender of sobriety checkpoints, called the roadblocks "a deterrent." "It doesn't matter that we don't make that many arrests," he said. "That's not the point." Mitchell said the relatively small number of arrests yesterday "speaks for itself. When we first started this in 1981, there were a lot more arrests. Now, we're seeing the intoxicated people in the passenger seats."

Sgt. Robert Fuller, one of 11 officers manning the roadblock, said he believes that the roadblocks are an important part of the current widespread campaign against drunk driving that has led to stiffer penalties and a flurry of offers from organizations for free taxi rides home for intoxicated holiday partygoers.

Most motorists didn't mind being stopped. As William Disney, a 60-year-old Maryland furniture salesman, approached the alcohol inspection point at the 5700 block of Allentown Road about 2 a.m., about two dozen cars had slowed down in front of him. Said Disney, who was returning from an Oxon Hill party, "I'd rather be delayed a few minutes than get hit by some drunk."

Squinting under the beam of Officer James O'Neill's flashlight, Disney answered the police officer's brief questions: "I drank two beers about two hours ago." As with each previous driver, O'Neill quickly checked Disney's eyes, appearance and breath for signs of alcohol and then waved him through the checkpoint.

If O'Neill had found any reason to believe Disney was intoxicated, he would have ushered him to a curbside stop and required him to go through a battery of sobriety tests, such as walking a straight line or reciting the alphabet. Motorists who fail those tests are arrested and asked to take a Breathalyzer test.

In spite of a delay of about five minutes, the overwhelming response from drivers and passengers was positive.

Some were dressed in tuxedos and satins, others in jeans and glittery "Happy New Year" cardboard hats, but almost all thanked the officers for working through the holiday. All, that is, but the four arrested.

"This is a rotten idea. It's a waste of time and money. I'm going to fight this in court," Jenkins said after he was arrested and charged with drunk driving. "Only in Maryland would they do this," he said. "It's against my rights."

While the Maryland courts have upheld the constitutionality of sobriety checkpoints, ruling that they are a legitimate measure against drunk driving, Virginia and District courts have yet to wrestle with the legal question of whether police should stop drivers when they have no reason to believe they have done anything unlawful.

Judges in South Dakota, Oklahoma and Illinois have recently ruled against the checkpoints, calling them a violation of the Constitution's Fourth Amendment protection against "unreasonable searches and seizures." But New York, New Jersey and Kansas courts have concurred with Maryland's approval of well-marked police roadblocks if they are brief and apply the same procedure to all drivers who pass through.

Any driver who does not want to submit to questioning at a sobriety checkpoint has the legal option to refuse, and does not have to roll down his window. But, as Fuller points out, if a driver argues about being stopped, he is giving the officer enough time to observe whether he is intoxicated.

Under Maryland law, once a police officer has "probable cause" to believe a driver has been drinking, he can test him with the Breathalyzer. If the person refuses, his driver's license is automatically suspended for 60 days.

In California, the American Civil Liberties Union is embroiled in a lawsuit against sobriety checkpoints. In a legal brief pending at the state Court of Appeals in San Francisco, the ACLU argues that if the increasingly popular tactic is upheld "it will not be long before the police establish roadblocks and checkpoints for investigations of other sorts of serious crimes."

Yesterday in Maryland, no one voiced those complaints. Even the passenger in Jenkins' car, Mary Ryan, a pharmaceutical technician at a District hospital, said she thought the roadblock was a "real good idea. If it saves even one accident."