As a former Indian American student went on trial for spying on his roommate, who later committed suicide, with another man, prosecutors called it a hate crime and the defence a stupid teenage prank.

In opening arguments on Friday at Dharun Ravi's trial, a Superior Court jury in New Brunswick, New Jersey heard two versions of a case that gay-rights advocates say underscores the problems of harassment and bullying faced by homosexual teenagers.

Ravi's roommate, Tyler Clementi, 18, committed suicide by jumping off the George Washington Bridge days after learning that Ravi had used a laptop webcam to secretly view him in a sexual encounter with another man.

"This isn't about Dharun Ravi having to like Tyler Clementi's (sexual) orientation," Middlesex County First Assistant Prosecutor Julia McClure told the jury.

"It's about having the decency to respect it."McClure called Ravi's actions "malicious and criminal," and argued that he set out to harass and intimidate Clementi because he was gay.

But Steven Altman, Ravi's lawyer, asked jurors to withhold judgment until they heard all of the facts, contending that the prosecution had put a "spin" on the case that was not supported by the evidence.

Ravi, who will turn 20 on Tuesday, is not a bigot and is not homophobic, Altman said. At the time of the incidents described in the criminal case, he said, his client was "an 18-year-old boy" beginning his first year in college.

"Don't rush to judgment. Keep things in perspective," Altman said during a 25-minute opening in which he used the word "boy more than a dozen times to describe his client. Ravi "might have been stupid," Altman said, "but he certainly wasn't a criminal. "Ravi, who dropped out of Rutgers, the New Jersey State University, after being arrested in October 2010, has been charged in a 15-count criminal indictment. He could be sentenced to up to 10 years in prison if convicted of bias intimidation, a so-called hate-crime offence.