A day after his teenage son was killed in a drive-by shooting, Luis Arvelo found some comfort in the arrest of a body shop worker suspected in the slaying. But that quickly evaporated hours later when he learned the man had been freed after posting a $33,000 bail bond.

Puerto Rico currently is the only place in the Western hemisphere where all people, including those charged with rape and murder, are always entitled to bail. But under an upcoming referendum that would allow judges in the U.S. territory to deny bail in certain cases, the man charged with killing Arvelo's son could have remained behind bars.

The referendum has sparked a debate on the island about the rights of suspects and those of victims and their families.

"It was painful to see this person and know that my son is 7 feet underground and he was out on the street," Arvelo said.

The right to bail has long been enshrined in the U.S. territory as a legacy of the islanders' historic distrust of American authorities, and Puerto Ricans have defended an individual's right to freedom, especially those who have been marginalized.

Elsewhere in Latin America and across the Caribbean, it's common for suspects to languish in jails even if they haven't been charged with anything. In the U.S., meanwhile, judges have the right to deny bail if someone has been charged with a violent crime or if prosecutors prove the suspect is a danger to the community or at risk of fleeing.

In Puerto Rico, legislators see the referendum as a way to fight crime and the perception among many that the violence is out of control, with police reporting a record number of killings last year. Gov. Luis Fortuno, whose party supports statehood, also seeks to align himself with U.S. authorities during an election year as Puerto Rico prepares for an unrelated referendum that would help decide the future of the island's political status.

Because Puerto Rico is a U.S. territory, its federal judges have the right to deny bail, and they have done so for 264 suspects out of 280 arrested for violent crimes, Fortuno said. "It is time that judges in Puerto Rico tribunals have the same discretion," he said.

The leader of Puerto Rico's main opposition party also supports the referendum, which is among several measures to fight crime, including a plan to create courts that will deal exclusively with murder cases and authorize the permanent revocation of bail for those charged with killing security guards, police officers and other judicial officials.

If approved by voters on Aug. 19, the measure would allow judges to refuse bail for certain kinds of murders: those that were pre-meditated, committed during a home invasion, during a sexual assault or kidnapping, or during a drive-by shooting, or targeting public officials.

However, voters in 1994 rejected a similar referendum, with 46 percent in favor and 54 percent against. Legislators said that earlier measure lost because it was too far-reaching and would have allowed judges to deny bail in any case, regardless of the crime involved.

In the latest referendum effort, a committee to fight the measure was formed last month by several prominent groups and institutions including Puerto Rico's Association of Lawyers, a local private university and the Council of Churches. "They are massacring the constitution of Puerto Rico," former senator Victoria Munoz Mendoza said at the committee's first meeting.

But crime victim advocates largely support the referendum, saying that victims and their relatives often fear pressing charges or testifying against someone they could run into on the small island if they are freed on bail.

Currently, Puerto Rico's constitution prohibits judges from denying bail or setting a bail considered excessively high, a determination left up to the interpretation of the court. Defense attorneys can also demand that a different judge establish a new bail if they don't agree with the original amount set.

"I have seen a case in which someone set a $1 million bond and someone else lowered it to $50,000 and it was posted," said Justice Secretary Guillermo Somoza.

During fiscal year 2010, there were more than 3,700 requests to lower the original bond, and judges granted most, Somoza said, adding that no department keeps statistics on the highest bail set.

Felix Arvelo was riding home in a friend's car in May 2010 when someone shot into the vehicle and hit the 16-year-old in the back of the head, killing him. The next morning, police arrested Juan Rosa Perez, a body shop worker they believe had personal issues with the boy.

Rosa remained free for the year and 10 days before the trial, according to the dead boy's father, who said he stayed at home for days at a time because he didn't want to run into the suspect in San Sebastian, a town of about 42,000 people an hour's drive inland from Puerto Rico's northwest coast.

"It wasn't out of fear," the elder Arvelo said. "One time I ended up in a fight with him."

Rosa was eventually found guilty and sentenced to 129 years in prison.

Arvelo said he's baffled by people who have had family or friends killed and do not support the referendum. "How is it possible that those people have gone through this situation and are not in favor?" he said.

Myra Rivera Torres, whose daughter was killed by a stray bullet in 1997 while at a club in historic Old San Juan, is among referendum opponents. No one was arrested in her daughter's killing.

"We don't want to take away anyone's rights," said Rivera, founder of a nonprofit group that seeks social justice and equality while still defending victims' rights. "A person is presumed innocent until they are found guilty. One has to think about these things objectively, not viscerally."

Rivera said her organization instead demands a more efficient judicial system that would award more protection to witnesses, noting that several have been killed in recent years.

But Luis Guillermo Romero, whose 19-year-old son was fatally stabbed last April, backs the referendum effort.

"The most important right that exists is the right to life," Romero said, adding that he understands others' objections. "People are suspicious about the government. As a result, they have a visceral reaction of doubting things that come from politicians."