Boston - Shortly after midnight, a 16-year-old boy is stopped by police and arrested as he walks down a street in Lowell. He's jailed overnight and brought into court the next day in handcuffs and shackles.

His offense: violating Lowell's teen 11 p.m. curfew.

The youth, now 20, claims the city's curfew is unconstitutional, and he and another boy who was arrested in 2004 are asking the state's highest court to strike it down, saying it illegally restricts their right to free movement.

The Supreme Judicial Court will hear the case Monday, and its decision could affect other cities and towns in Massachusetts with similar curfews, including Chicopee, North Adams, and Lynn.

Lowell enacted the curfew in 1994 as it wrestled with an increase in gang violence, including an fatal, baseball bat attack on a 16-year-old boy in a city park. The curfew prohibits teens under 17 from being out between 11 p.m. and 5 a.m.

Attorneys for the men bringing the case, whose names were not made public because they were juveniles at the time, say there is no proof the curfew has accomplished what its supporters said it would do: curb crime and protect juveniles.

"It's just kind of a shot in the dark ? and they hope it will work ? but when you are restricting someone's constitutional rights, that's not good enough," said Boston attorney James Sultan.

Lowell is one of more than 200 cities and towns across the country that passed curfews in the 1990s in response to concerns about gang violence and juvenile crime.

Legal challenges to the curfews have had mixed results.

Curfews in Dallas, Washington, D.C. and Charlottesville, Va. have been upheld by courts, but curfews in Vernon, Conn., Rochester, N.Y., and San Diego have been ruled unconstitutional.

The challenge to Lowell's ordinance is the first time the Massachusetts high court has been asked to rule on the constitutionality of a curfew.

Sultan said the boy who was held in jail overnight was not causing a disturbance when he was approached by a police officer who was on routine patrol. The boy, who was visiting from Somerville, told police he was on his way to see a friend.

Lowell police say they usually don't arrest teens they find out during the curfew hours, but instead drive them home or to the police station, where their parents are called and asked to come pick them up.

"We certainly don't just walk up to you and say you are in violation of the curfew ? boom, you are under arrest," said Capt. Randall Humphrey, a police spokesman.

Police can arrest violators or fine them up to $300. The curfew has several exemptions, including for teens traveling to or from work, or for those attending a school or religious activity.

From 2005 to 2007, 28 juveniles were arrested for curfew violations in Lowell. Last year, only two were arrested.

Supporters say curfews give police a useful tool.

"We had some serious gang issues. It was almost constant, calls about five, six, seven or eight teenagers walking down one of the main streets at 11:30 at night," said Mayor Edward Caulfield, a supporter of the curfew.

"This gave the police department the right to stop and ask, 'What are you doing out this late? and Where do you live?' It was certainly a wakeup call not only to the kids, but to the parents."

But those who are challenging the curfew point out that most of the crime involving juveniles occurs in the afternoon hours, just after school gets out, so the curfew does nothing to help teens during their most vulnerable time of the day.

Opponents also say it has a disproportionate impact on minorities, particularly Cambodian youth, who may not understand why they are being stopped by police. Lowell has the second-largest Cambodian immigrant community in the country.

"Many of them have parents and grandparents who are refugees of the Khmer Rouge, and that experience results in fear of authority," said Cecilia Chen, a staff attorney at the Asian American Legal Defense and Education Fund.

State prosecutors who are defending the curfew say juveniles do not have the same rights as adults, citing laws that prohibit minors from purchasing alcohol and restrict the hours when young drivers can be on the road.

"The city of Lowell similarly has a legal right to place this curfew restriction on minors under the age of 17 to better protect their community," Middlesex District Attorney Gerry Leone said.

Lucky San, 16, who emigrated to Lowell two years ago from Cambodia, said he supports the curfew.

"I think it's a good thing because it prevents teenagers from getting into trouble, like participating in drinking, parties and things like that," he said.