The touchy question of how far U.S. power extends in Puerto Rico is at issue again, this time pitting the U.S. District Court here against the Puerto Rican Supreme Court and the commonwealth Senate in two separate cases.

In one, a sensational police case, the federal court quashed Senate subpoenas that would have forced 10 policemen to testify at televised hearings. In the other, the federal court contravened the Puerto Rico Supreme Court, which had suspended two lawyers for refusing to pay Puerto Rico Bar Association dues.

However, both cases were appealed to the 1st U.S. Circuit Court of Appeals in Boston, which stayed the District Court's actions.

Lawyers in San Juan generally welcomed the stay orders. Attorney Angel Viera said the Boston court better maintains the equilibrium between the federal and insular judicial systems. Superior Court Judge William Fred Santiago remarked that "the Boston court is more cautious, more respectful of local law."

But Speaker of the House Severo Colberg called for a movement to oust the U.S. District Court from Puerto Rico, calling it "an enclave which serves the interests of the U.S. government's imperialistic work."

The U.S. District Court of Puerto Rico, with its English-language proceedings and total reliance on U.S. precedents, always has been viewed by critics here as an anomaly in a Spanish-speaking society where all other courts operate in Spanish and base decisions, in civil cases, on 19th Century Spanish codes.

The two current controversies, moreover, are thoroughly entangled in local politics. The six federal district judges, all Puerto Ricans, favor statehood for the island. By contrast, six of the seven justices on the Puerto Rican Supreme Court favor the island's semi-autonomous commonwealth status.

The bar association is dominated by attorneys favoring a broader autonomy or outright independence from the United States. And the Senate is controlled by members of the pro-commonwealth Popular Democratic Party PDP , who have found in the police case a chance to embarrass the administration of pro-statehood Gov. Carlos Romero Barcelo.

The so-called Cerro Maravilla case began July 25, 1978, when two youthful independentistas were killed by police near a television relay tower atop remote Cerro Maravilla Mountain in central Puerto Rico. Police said Carlos Soto Arrivi, 18, and Arnaldo Dario Rosado, 24, both members of a tiny terrorist group called the Armed Revolutionary Movement, had intended to sabotage the tower and died in a shootout.

The two youths were accompanied by a young police informer and the driver of a taxi the youths had commandeered at gunpoint. The undercover agent was wounded slightly.

The police said they had acted in self-defense, and Romero quickly hailed them as "heroes." However, journalistic enterprise and partisan political interest soon gave rise to widespread suspicions that the youths were ambushed, wounded, brutally kicked and then murdered.

The rising clamor prompted two investigations by the commonwealth Justice Department and two federal grand jury probes with FBI help. None found sufficient ground to indict the police. But accusations of a possible cover-up prompted the Senate to launch televised hearings.

The Senate hearings revealed that both commonwealth probes had been shoddy. A district attorney had failed to order ballistics tests, and a top Justice Department criminal investigations chief had refused to take testimony from a police officer who said he heard a second volley of shots--which corroborated statements to reporters by the cab driver.

In the midst of the hearings, San Juan Star newsman Manuel Suarez disclosed an internal U.S. Justice Department memo showing that the first FBI investigation was limited to reviewing reports in newspapers and of the commonwealth Justice Department. The memo states "that a full preliminary investigation was inadvisable as such investigation would be seized upon by elements of the press in an attempt to discredit the government of Puerto Rico."

As the televised Senate hearings continued, the embattled taxi driver appeared and confirmed under oath that he had seen the youths beaten and had heard a second volley of shots.

But with public interest soaring, the hearings were halted suddenly when U.S. District Judge Juan Perez Gimenez quashed the Senate subpoenas calling 10 policemen to testify. The policemen, defendants in a $2 million damage suit filed by relatives of the slain youths, argued that the televised hearings could prejudice their case. They offered to testify in closed-door executive session.

In quashing the subpoenas, Perez Gimenez agreed that public hearings would encroach on the plaintiffs' right to an impartial jury. The judge also said the court "cannot assume that the Senate of Puerto Rico will react responsibly in protecting the plaintiffs' right to a fair trial."

Senate President Miguel A. Hernandez Agosto insisted that the federal court cannot invade the legislative province, adding that "we don't have to give explanations" to the federal court.

The Senate Judiciary Committee then sought, and won, a stay of the order from the 1st U.S. Circuit Court of Appeals, permitting resumption of the televised hearings. Attorneys for the police said their clients had nothing to hide and would testify.

Meanwhile, another U.S. district judge, Juan M. Torruella, was stirring up another controversy. Rejecting an earlier decision by the commonwealth Supreme Court, he ruled that the compulsory payment of dues to the Puerto Rico Bar Association is an unconstitutional requirement for practicing law.

The Torruella ruling came on a civil rights complaint filed by attorneys Hector Ramos and Robert Schneider, who had refused to pay the bar association's $100 annual dues because they objected to the association's pro-autonomy political activities.

The Commonwealth Supreme Court supported the mandatory dues and suspended the two lawyers. Chief Justice Jose Trias Monge found that the bar associations of old Spain, and the original Puerto Rico bar association founded in 1840, all had compulsory membership.

After the United States acquired Puerto Rico in the 1898 Spanish-American War, the military governor suppressed the local bar association and a voluntary association of lawyers was created. Trias Monge called it "a pallid entity that lived precariously" until the current compulsory bar association was created in 1932.

While he recognized that some accommodation must be made for attorneys who object to having their dues used for ideological activity that they oppose, the chief justice stressed that the public interest in creating a "vigorously pluralistic society, the improvement of the legal professional and the proper march of the judicial system far outweigh personal inconveniences that mandatory management may entail."

With their suspensions thus upheld, attorneys Ramos and Schneider decided to appeal. But instead of going to the U.S. Supreme Court--supposedly the only court which can overturn the Puerto Rico Supreme Court--they filed a civil rights complaint with U.S. District Court here.

Judge Torruella, a man with no sympathy for the pro-autonomist inclinations of the bar association, decreed that as long as the bar association persists in its "massive" ideological and/or political activism, the Puerto Rican government could not collect revenues for the bar association through the sale of notorial and forensic stamps. Further, he ruled, no actions could be taken against lawyers for failing to pay dues.

The bar association, like the Senate, then prepared an appeal to the federal appeals court in Boston. In the meantime the court granted a stay permitting the bar association to collect some $24,000 in stamp proceeds held in escrow by the government. Stamp sales are to resume.

Association officials note that association bylaws already earmark 55 percent of the stamp income for members' life insurance. Hoping to bury that part of the dispute, they say they will press for an amendment earmarking 100 percent for that "clearly non-ideological" purpose.