A federal judge sentenced environmental lawyer Robert F. Kennedy Jr. to 30 days in prison Friday for trespassing while attempting to thwart U.S. Navy bombing exercises on Vieques island.

Several other protesters were convicted along with Kennedy, including New York labor leader Dennis Rivera and Norma Burgos, a senator in Puerto Rico's legislature.

"You should be a lawmaker not a lawbreaker," Chief U.S. District Judge Hector Lafitte told Burgos, sentencing her to 40 days. When she said that the Navy should be tried instead of the protesters, Lafitte called her defiant and increased the term to 60 days in jail. Rivera and three others were given 30-day prison terms.

He dismissed arguments that the protest was for the greater good – to end contamination of the environment and save islanders' health.

Kennedy and the others were among some 180 people arrested for trespassing during exercises with dummy bombs in late April and early May on the Puerto Rican island. They include actor Edward James Olmos and U.S. Rep. Luis Gutierrez, a Democrat from Illinois, who have yet to go on trial.

The Rev. Al Sharpton and Jacqueline Jackson, the wife of the Rev. Jesse Jackson, were among protesters recently jailed. Mrs. Jackson served a 10-day sentence last month. Sharpton was sentenced to 90 days because it was his second conviction and is to remain behind bars in New York City until Aug. 15.

Several people gathered outside the courthouse Friday to speak in support of the other protesters, including Jesse Jackson and Democratic Reps. John Conyers of Michigan and Nydia Velazquez of New York.

Before entering the courtroom, Kennedy said he was ready to go to jail. But supporters said it was poor timing, as his wife is expected to give birth to their sixth child next week.

Kennedy's lawyer, former New York Gov. Mario Cuomo, had planned to use the trial to argue for a political solution to end six decades of bombardments on the Navy's prized Atlantic firing range. But Lafitte refused to hear that line of argument, saying "I'm not going to allow political views, philosophical views, none of that."

Assistant U.S. Attorney Peter Strasser took testimony from Navy officers who said that Kennedy and Rivera's incursion – from a fishing boat onto the beachside firing range –forced a halt in the exercises.

"As soon as the vessel, the boat, entered the danger zone, I had to cease fire," said Lt. Cmdr. Russell Gottfried.

He said he interrupted the ship-to-shore shelling for 2 1/2 hours while security officers scoured the range for Kennedy's party, which was hiding in mangroves.

Kennedy, the nephew of the late President John F. Kennedy, said he is glad that since he was arrested, President Bush has announced that the Navy will stop bombing exercises on Vieques by May 2003.

But, he said, "That position begs the question, why are we going to continue bombing?"

Kennedy and other opponents argue the bombing harms the environment and the health of the island's 9,100 residents – charges the Navy strongly denies.