A year after Grenada's revolution exploded in violence and prompted a U.S. invasion, 19 islanders went on trial for murder today in connection with the slaying of prime minister Maurice Bishop during a bloody power struggle.

All 19 refused to plead guilty or not guilty, calling themselves prisoners of war and questioning the court's authority under "foreign occupation" to organize a trial and submit them to risk of the death penalty. The gesture appeared designed to highlight what is expected to be a challenge to the constitutionality of actions by U.S. troops and Governor General Paul Scoon during and since the invasion last Oct. 25.

U.S. forces, after securing a formal request from neighboring islands, seized control of Grenada following a bloody confrontation Oct. 19 between Bishop, who led the leftist revolution here in 1979, and Bernard Coard, his chief aide who had pushed out Bishop amid accusations he was running a one-man government and betraying Marxist-Leninist principles.

"Under foreign occupation, I do not recognize the legality of this court," declared Coard's wife Phyllis, who also is charged.

"This court has been duly . . . ," Coard began when it was his turn to plead, apparently seeking to explain the group's actions.

"Mr. Coard, I am not asking for a speech," Judge Archibald Nedd cut in sharply. "I am asking whether you are pleading guilty or not guilty."

Delano Harrison, a Jamaican lawyer who was part of the defense team during pretrial hearings last summer, said the revolutionary leaders are likely to cite the constitutionality issue. Most were captured by U.S. forces soon after the invasion and interrogated by U.S. intelligence officers.

One hour into this morning's proceedings, Phyllis Coard fell heavily from a sitting position. Panting loudly, she shouted in a hoarse voice that she has been on a hunger strike for the last six weeks and has been refused requests to be examined by a doctor from outside the island.

"The occupation forces have not allowed me to have a doctor of my choice," she added. "They have not allowed me to see my lawyer for eight weeks. They have not allowed me to see my family."

As she was carried limp from the sultry courtroom by female constables, Nedd ordered that she be examined separately by a doctor named by the court, a second doctor named by the prosecution and a third from abroad at the expense of her family.

"But I must say," added the judge, "Mrs. Coard's voice sounds strong to me."

Coard shouted that his wife's apparent fainting spell was the result of "a reign of terror against all of us" under prison commissioner Lionel Moloney, a Barbadian officer seconded to the 400-man Caribbean police force that, along with 250 U.S. military police and support troops, has been enforcing Scoon's authority.

None of the 19 was represented by a lawyer. Harrison said the families expect to raise enough funds within "a few months" to retain lawyers. But Nedd replied he has no intention of waiting that long and said the court will resume the trial Nov. 1, with appointed lawyers if necessary.

The 19 defendants made up the top leadership of the People's Revolutionary Army and the Revolutionary Military Council that ruled Grenada's 100,000 inhabitants for six fearful days between Bishop's death and the U.S. invasion.

The popular Bishop had been forced out of the ruling New Jewel Movement central committee over a doctrinal leadership dispute and put under house arrest. But a crowd, consisting largely of schoolchildren, forced his release four days later, leading to the showdown with Army troops that resulted in Bishop's death along with an estimated 100 others.

The defendants have been charged with murder, a capital offense under Grenada's British-based law, in 11 of those deaths which were apparent executions. The others in the group of 100 died in a clash with troops.