The hate crime trial of a white teenager accused of bludgeoning a black man with a baseball bat in Howard Beach last summer opened yesterday, with prosecutors describing the attack as unprovoked racial violence and the defense depicting it as community policing.

The defendant, Nicholas Minucci, 19, is charged with assaulting Glenn Moore, 23, with a 34-inch aluminum Louisville Slugger in the early morning hours of June 29. The assault is being charged as a hate crime, and carries a penalty of up to 25 years in prison if he is convicted.

Mr. Moore, who suffered a fractured skull, survived the attack and is expected to testify.

In the days following the assault last year, many observers drew parallels between it and an assault that riveted the city nearly two decades ago, in the same neighborhood, in which a group of whites assaulted several men, one of whom, Michael Griffith, was hit by a car as he fled onto the Shore Parkway and died. The new case is being tried in the same state courthouse in Kew Gardens, Queens, where several men were convicted in the 1986 attack.

At the time of last summer’s attack, Mr. Minucci was accompanied by two acquaintances, both white, one of who has pleaded guilty to attempted assault as a hate crime and attempted robbery. Mr. Moore also was with two acquaintances, both black.

Prosecutors said Mr. Minucci was out driving at around 3 a.m., when he spotted Mr. Moore and his companions. Mr. Minucci “glared” at Mr. Moore and the others from the window of his luxury Cadillac Escalade, an assistant district attorney, Mariela Herring, told the jury yesterday. “If they were three whites, he would not have given them a second look,” Ms. Herring said.

According to the prosecution, Mr. Minucci drove away, but returned later with at least one friend and chased Mr. Moore down on foot. When he caught up to Mr. Moore, he used a racial epithet and struck Mr. Moore several times with the bat, including once in the head, Ms. Herring said. The incapacitated Mr. Moore was then stripped of the athletic shoes he was wearing, she said.

The trial will turn in part on Mr. Minucci’s admitted use of the “n-word,” and what its current meaning in youth parlance is. During jury selection last week, the prosecution quizzed prospective jurors about their reactions to hearing the word.

Mr. Minucci’s attorney, Albert Gaudelli, called the attack “a minor dustup between six young men,” and argued that Mr. Minucci’s actions comprised vigilant citizen policing.

“Is there anything illegal about chasing someone out of the neighborhood? They were using reasonable physical force to prevent a larceny,” Mr. Gaudelli said. Employing racial imagery, he asserted to the jury: “And it as clear as the nose on your face, or the color of your skin, that they were here to commit a robbery.”

The prosecution acknowledged that Mr. Moore and his two friends had ventured into Howard Beach in order to steal a car, but said that information is irrelevant to the charges against Mr. Minucci.

“They were not wearing a sign, reading ‘I’m here to steal a car,'” Ms. Herring said. Referring to the defendant, she said: “For him, the color of their skin was like wearing a sign that read: criminal.”

The first witness, an emergency responder who encountered Mr. Moore in the minutes after the attack, Efrin Renden, told how Mr. Moore was bleeding from his ear, and was trembling uncontrollably before undergoing seizures.

In the dim court room of the Queens County Courthouse in State Supreme Court the most noticeable reaction to the testimony came not from the jury, but from Mr. Minucci’s friends and his mother, who occupied several rows of the courtroom. When Mr. Renden was unable to recall certain details relating to whether Mr. Moore was wearing a hat at the time, audible snickering could be heard from the section of Mr. Minucci’s supporters.

For the jury, the main question will be to decide what prompted the altercation: Mr. Minucci’s alleged hostility towards blacks, as the prosecution argued, or Mr. Minucci’s notion that Mr. Moore was about to commit robbery, as Mr. Minucci’s attorney maintains. The case is before Judge Richard Buchter.