SAN JUAN, Puerto Rico -- Environmental lawyer Robert F. Kennedy Jr. and New York labor leader Dennis Rivera were found guilty Friday of trespassing on Vieques Island to protest the U.S. Navy's bombing exercises.

Chief U.S. District Judge Hector Laffitte sentenced Kennedy and Rivera to 30 days in prison after hearing moving arguments from attorneys.

Five others also received 30- to 60-day sentences, including Myrta Sanes, sister of a civilian guard killed by off-target bombs on the Vieques range in 1999, and pro-statehood Puerto Rican Sen. Norma Burgos.

The death of guard David Sanes sparked protests in Puerto Rico against the use of the island for military exercises.

Protesters say bombing of the island poses a health threat, contending uranium was used on shells and rockets, and explosions placed contaminants from the site into the air. Navy officials counter the exercises are necessary for national security.

However, the Navy and Marine Corps face a deadline in two years to find other locations to carry out their drills. Islanders are expected to vote on a referendum on whether the Navy stays or leaves Vieques. Also, President Bush has said the bombing exercises on the island will stop in May 2003.

Kennedy, son of slain Sen. Robert F. Kennedy, was detained in April with actor Edward James Olmos and U.S. Rep. Luis Gutierrez (D-Ill.). Olmos and Gutierrez have yet to go on trial.

Other protesters were convicted earlier, including Al Sharpton and Jacqueline Jackson, wife of Jesse Jackson, who was in attendance Friday. Jacqueline Jackson served a 10-day sentence last month; Sharpton received a 90-day sentence.

Former New York Gov. Mario Cuomo, Kennedy's defense lawyer Friday, sat silently in the courtroom nearly all day as Laffitte held a tight rein on the band of lawyers surrounding the celebrity defendants and others.

Back and forth went the caustic exchanges between the defense lawyers and Laffitte, who began by warning them: "I'm not going to allow political views, philosophical views, none of that."

But political and historical tones shadowed the day. By the end, when Cuomo rose to deliver a closing statement, he mesmerized the courtroom, invoking the celebration of Independence Day and the history of civil disobedience. But his impassioned defense failed to sway Laffitte, whose sentences jolted the high-powered lawyers.

The lawyers argued that because Bush recently changed policy and had ordered the bombing tests stopped by 2003, there was no longer a need to impose jail sentences that might dissuade others from joining in the demonstrations.

"Because there appears now no urgent need to deter them or others from the kind of massive protests that occurred in the past, we ask that the defendants, having been found guilty of civil disobedience, be sentenced to time served," Cuomo said.

Laffitte was unmoved as he handed out the sentences to Kennedy and Rivera, the president of New York state's largest health-care workers union.