A British magistrate ruled today that Augusto Pinochet can be extradited to Spain to face a criminal trial for alleged human rights abuses during his years as president of Chile. But the future of the Pinochet case--regarded as a key precedent in the emerging field of human rights law--could depend more now on political and diplomatic decisions than on legal questions.

Anti-Pinochet protesters and human rights activists shouted and danced in the streets outside the Bow Street Magistrate's Court when the decision was announced, and demonstrators in the Chilean capital of Santiago reacted similarly. Pinochet's lawyer read a strongly worded statement that said that his client is innocent and that the criminal case "is being pursued primarily for political reasons."

The former general has been under house arrest in a mansion outside London for nearly a year pending a decision on extradition. A Spanish prosecutor wants to take Pinochet to trial in Madrid on 35 counts of torture and conspiracy to torture his political adversaries during the 17 years he ruled Chile as the head of a military junta.

Pinochet has described himself as a "warrior," and he has waged intense legal battles at every stage of the case. But in the next 15 days, the veteran commander will have to make one of the most important tactical decisions of his life.

He has 15 days to appeal today's ruling. If he does, the legal arguments would delay any further action against him, probably for about another year.

But Pinochet, 83, has repeatedly said that what he wants most is to go home to Chile. To achieve that goal, Pinochet might gamble by dropping his legal appeals and instead try to win his freedom through politics and diplomacy.

Today's decision by Magistrate Ronald Bartle was narrow in scope, saying only that Britain can legally extradite the defendant to Spain. But the ruling is not an extradition order. Under British law, extradition can be ordered only by the home secretary, a cabinet minister roughly equivalent to the U.S. attorney general.

The home secretary, Jack Straw, has broad discretion under the extradition law. He could choose to end the case and send Pinochet home to Chiler on a variety of grounds, but only after all legal appeals are exhausted.

So Pinochet might choose to forgo his right to appeal and hope for a favorable decision from Straw. Diplomats working on the case say that strategy is under consideration. Pinochet's lawyer, who has appealed immediately after every other adverse ruling in the case, said nothing today about filing an appeal.

Straw was a human rights activist in the 1970s and joined anti-Pinochet rallies in London. Today, though, he is a more centrist politician. And he has been criticized by conservatives here for showing disrespect to Pinochet, an old British ally. Straw, who recently decided that an 87-year-old British woman accused of treason should not be brought to trial, has also been accused of following a double standard in arresting Pinochet.

If he decided to set Pinochet free now, Straw would presumably have to get the Spanish government to agree. But that agreement might come readily; Spain's centrist government has clearly been uncomfortable with the prosecutor who brought charges against Pinochet.

Even the international human rights movement might not be seriously upset if Pinochet were released. The case Kingdom of Spain v. Pinochet has already produced a landmark ruling with global implications. Britain's highest court ruled in March that a former head of state accused of human rights abuses in violation of international treaties can be brought to trial in virtually any country.

"Pinochet should face justice for his crimes," said Reed Brody, of New York-based Human Rights Watch. "But even if the case ended now, it has clearly established the precedent of universal jurisdiction over tyrants who commit crimes against humanity."

If Pinochet were to ask the home secretary to allow him to go home to Chile, the rationale would most likely be his health. He might argue that he is no longer strong enough to stand the pressure of a trial that would review numerous cases of imprisonment, torture, and killing in Chile's jails during his rule.

Pinochet's British doctor says his patient is suffering from depression and other ailments. He says Pinochet has had two minor strokes in the past month. When the second stroke occurred, on Sept. 25, a priest was summoned to administer last rites, the doctor said.

Officials from Chile's democratic government, which has called for Pinochet to be tried in his homeland and has lobbied for his release on grounds that only Chile has jurisdiction for crimes committed during his rule, criticized today's ruling for interfering with Chile's domestic affairs. The government said it will press forward with attempts to win Pinochet's release because of his failing health.

"We have taken this [verdict] with calm, because we have presented all the data which proves Pinochet's health is extremely concerning," said Chilean Foreign Minister Juan Gabriel Valdes. "And we will insist on his release for humanitarian reasons by issuing [more] medical and technical reports to be considered by Jack Straw."

In Santiago, Pinochet's conservative supporters said that British government intervention to release Pinochet because of his ill-health is the best hope to avoid his trial in Spain. More than 300 of these supporters gathered for an all-night vigil at the Pinochet Foundation, a charity organization that also promotes the former dictator's image.

"This is the worse possible outcome," Luis Cortes Villa, executive director of the Pinochet Foundation, said as children in a preschool next door to the foundation chanted "Return Pinochet" to reporters gathered in a courtyard. "It leaves me to believe that the only way my general will return to Chile is if his grave health condition is considered by the British. . . . He is too ill to be able to survive the prolonged legal process, and [the British authorities] must recognize that."

Correspondent Anthony Faiola in Santiago, Chile, contributed to this report.