Decision Could Discourage Other Efforts to Abduct Suspects : Arrests: If upheld, the ruling would change the ground rules under which U.S. law enforcement can operate on foreign soil.

Even after the kidnaping of Dr. Humberto Alvarez Machain set off howls of protest from Mexico, officials of the Drug Enforcement Administration refused to rule out further abductions to bring the suspected killers of agent Enrique Camarena to justice in the United States.

“The mission is simple,” one official declared. “Track down and eliminate all persons involved in the kidnap, torture and murder.”

But a federal judge’s ruling Friday that Alvarez was illegally brought to the United States in April could end plans for any more such backdoor deliveries of Camarena case suspects.

In addition, if upheld on appeal--a process almost certain to go to the U.S. Supreme Court--the stinging criticisms voiced by U.S. District Judge Edward Rafeedie would change the ground rules under which the DEA and other federal agencies occasionally have used bounty hunters and other espionage-like methods to capture drug traffickers and terrorists on foreign soil.

“I’m real pleased to see it,” said Michael Pancer, a defense attorney who represented the first of three Camarena case suspects who were abducted and brought to the United States. “I think they’ve been operating in an illegal fashion and finally somebody’s called them to task for it.”

In each of the three Camarena case abductions, federal agents relied on shadowy operatives or cooperative foreign law enforcement officials to seize suspects and deliver them to U.S. territory.

The agents’ top-secret actions have been guided by a century-old legal precedent, in which the Supreme Court upheld larceny and embezzlement charges brought in Illinois against a man who had fled to Peru, where he was seized by an American private detective and forced onto a boat home. The justices said, in effect, that it did not matter how the suspect was obtained--merely that he was before the right court.

In more recent years, federal courts have carved out one exception to that rule, invalidating an abduction in which a suspect was tortured in a manner “shocking to the conscience.”

But Rafeedie declared a new standard for invalidating such kidnapings. The DEA, he said, “unilaterally abducted” the Guadalajara physician in violation of the extradition treaty between the United States and Mexico. And one fact was central to the ruling--that the Mexican government had formally protested the abduction.

In other cases in which suspects have been abducted to the United States, the judge noted, the foreign governments did not file such objections--thus giving tacit approval.

“I think that it’s a very courageous decision,” said Abraham Abramovsky, director of the International Criminal Law Center at Fordham University in New York. “The reason you have an extradition treaty is to comply with international law and enhance the relationship between the two countries. Once you have it, there’s no reason not to go with it. . . . “

Although DEA officials and federal prosecutors declined to comment on the ruling Friday, they repeatedly have defended the use of extraordinary tactics to pursue suspects in the 1985 slaying of Camarena, who was snatched off the streets of Guadalajara and then tortured in an attempt to force him to tell what the DEA knew about Mexican drug traffickers.

U.S. officials complained that, despite the 1978 extradition treaty, Mexico has refused to turn over its own citizens for prosecution, insisting that they be tried in Mexico instead.

The first abduction was carried out in January, 1986, when Rene Martin Verdugo Uriquidez was taken from his car in Mexico by six men--including four State Judicial Police officers--and then stuffed through a hole in the border fence into the arms of U.S. agents. A spokesman for the U.S. Marshals Service said its agents “just happened” to be waiting with arrest warrants when Verdugo popped through the fence.

Two years later, there were riots in Honduras when that country’s popular drug lord, Juan Ramon Matta Ballesteros, was forced on an airliner by local police, then arrested over U.S. airspace.

In four separate appeals in U.S. courts, Matta’s attorney has sought to have U.S. charges dropped because of the way he was brought into the country. But the Supreme Court has refused to hear the appeals and Matta was convicted last month in federal court in Los Angeles of conspiring in Camarena’s murder.

Matta’s attorney, Martin R. Stolar, was not optimistic Friday that Rafeedie’s ruling would help his client.

“The major distinction is that the government of the Republic of Honduras has not opened its mouth,” he said. “. . . It must file a formal protest, reflecting the will of the people who protested so vehemently when Matta was kidnaped.”

The issues discussed by Rafeedie have repercussions well beyond the single case.

In a controversial legal opinion last year, a high-level Justice Department official said mounting terrorist and drug threats gave the FBI authority to seize fugitives overseas without a foreign country’s permission.

In a prominent 1988 case, the FBI arrested a suspected Lebanese terrorist after he was lured by a former associate onto a yacht in international waters.

The outcome of Alvarez’s appeal clearly could affect the prospects for “Operation Leyenda,” the Camarena investigation being carried out by a DEA task force in Los Angeles.

Just this week, U.S. Atty. Lourdes G. Baird vowed that the investigation would not end with the four convictions just obtained in federal court. “The government of the United States will spare no effort or expense in its continuing investigation,” she said.

Baird declined to elaborate, but the suspects already indicted here--but not in U.S. custody--include Miguel Ibarra Herrera, the former head of Mexico’s Federal Judicial Police, and Manuel Aldana Ibarra, the former head of the Mexican equivalent of the DEA.

The DEA is also known to be investigating Mexico City Chief of Police Javier Garcia Paniagua.

In addition, the controversial DEA operative who arranged the seizure of Alvarez once noted with a smile that a second Mexican physician was also suspected of helping in the torture of Camarena. “He hasn’t been indicted yet,” Antonio Bustamante Garate said in an April interview with The Times. “I hope he will. Then I will look for him.”

Under the legal guidelines outlined by Rafeedie, the Mexican government effectively would have veto power over any attempt to secretly slip suspects across the border--thus dooming such operations.

“I think that the DEA in this particular case overreacted, and I understand why. One of their own was killed,” said Abramovsky, the Fordham professor. “On the other hand, the DEA has to be guided by the agencies of the government in charge of foreign relations . . . I think the judge sent a message to the DEA and the Justice Department to come up with a coherent and cohesive policy.”

Times staff writer Henry Weinstein contributed to this story.