LOS ANGELES (AP) — College student Christian Rodriguez was heading home from his girlfriend's house when two police officers threw him face-down on the ground, clapped him in handcuffs and arrested him.

His offense? Being out past 10 p.m.

Police said the 20-year-old is a gang member and subject to a sweeping court injunction covering the housing project where he lives. The injunction lets police enforce a nighttime curfew and arrest people for hanging out in public and wearing gang colors.

The soft-spoken Rodriguez has no adult criminal record and claims he was never in a gang, though police maintain he was an active member in his early teens. Like dozens of other young men who dispute their gang label, he faces an uphill task trying to clear his name.

Authorities nationwide are increasing the use of such injunctions, saying they help reduce gang crimes. But civil rights groups insist police are casting too wide a net and snagging innocent people.

"They see me out there and say I'm out there gang-banging, but I'm not," said Rodriguez, a straight-A student at an alternative high school who also attends college classes and recently won a scholarship to study for an associate's degree. "I feel like I'm locked up. I can't do nothing."

In Los Angeles alone, 43 injunctions covering 71 gangs and about 5,500 alleged gang members are in place. The tactic is also employed in several states beyond California, including Texas and Florida.

Authorities say dropping crime rates are proof that injunctions work. In one case, officials credit an injunction for transforming MacArthur Park in downtown Los Angeles from a place where killings and drug deals were common to a popular recreation area.

In the nearly 10 years since the injunction at the Mar Vista Gardens housing project became permanent, overall gang crime at the west Los Angeles complex has been cut in half, police figures show. Individuals convicted of violating terms of an injunction can face up to six months in jail, as well as a $1,000 fine.

"It has been a silver bullet for us," said Lt. Nicholas Sinibaldi, who oversees area gang operations. "It's been a big part of why gang crime has dropped."

At Mar Vista, the rows of barracks-style apartment buildings are splayed along the concrete banks of a creek. A few miles from the beach, the project is the historical home of the Culver City Boys, a largely Latino gang that has waged war against nearby rivals such as the Venice Shoreline Crips.

Since the injunction was implemented, some residents including Rodriguez say they have been wrongly identified as gang members and unfairly subjected to the injunction. They say they have lost basic freedoms like the ability to visit relatives in certain neighborhoods.

Kim McGill, an organizer with the activist group Youth Justice Coalition, said injunctions can bar people from moving freely through their neighborhoods, making it almost impossible for young men to travel to jobs in other parts of town, she said.

"It isolates people physically or mentally," McGill said. "It pushes them back into an underground economy because the options for you are significantly reduced."

Jose Herrera, a 23-year-old former Mar Vista resident who recently returned to play basketball, said he and his family were evicted from the project because he was accused of violating terms of the injunction.

Public housing rules mean tenants can be evicted if they engage in gang crime.

Like Rodriguez, Herrera says he was unfairly labeled a gang member.

"It's basically like I'm in jail," said Herrera, who on occasion returns to the housing project to play basketball, even though he is not supposed to be there. "I've got no freedom."

Still, in many neighborhoods where injunctions have been implemented, the sense of improvement is palpable. In MacArthur Park, kids play soccer and families use an outdoor gym where gangs once sold fake green cards and attacked park users.

"Before, people couldn't go in there," cook Eduardo Osorio, who works at a chicken grill next to the park, said in Spanish. "Now it's much calmer. Things have changed, it feels safe."

Civil rights groups and individuals have filed numerous legal challenges against injunctions, arguing that they infringe on constitutional rights such as freedom of association.

Attorney Olu Orange got the case stemming from Rodriguez's arrest dismissed in part because he argued that the language in the injunction was invalid. Rodriguez remains subject to the injunction itself.

"Gang injunctions are a hurried, unconstitutional effort to deal with a very real problem," said Orange, who plans to sue the city to force it to redraft the lawsuits.

People who are subject to an injunction can challenge the decision in court or file a petition with the city attorney's office asking to be removed. Even though it's free, few do so, saying the system is stacked against them.

Others, like Herrera, said they had never heard of the petition process. The city attorney is trying to counter that by sending deputies into the field to tell residents how they can apply to be removed from a gang injunction.

Of the 49 people to have filed a petition since the process was established in late 2007, only three have been successful in challenging their status. Other applications were rejected or are still being considered.

Police use street intelligence to classify someone as a gang member and make him subject to an injunction. Criteria can include using gang hand signs, wearing gang clothing or testimony from another member.

Opponents say it's unfair for police to serve an injunction based only on an officer's opinion about someone's suspected gang ties.

"You are essentially giving the powers of the judge to a police officer," said Hooman Kazemi, a deputy public defender for Los Angeles County. "An officer can make a decision that someone is subject to a court order without judicial review."

Bruce Riordan, who heads the gang division for the Los Angeles city attorney's office, said any time an officer serves someone with an injunction, that decision must be approved by prosecutors.

Kazemi and other attorneys say they've seen dozens of clients who claim not to be in gangs end up in court anyway, facing stiff penalties for violating an injunction, sometimes just for walking through a prohibited neighborhood.

California Sen. Rod Wright proposed a bill that would have granted an automatic five-year sunset to an individual's placement on an injunction, provided they commit no crimes in that time.

The bill, which failed, was spurred by a meeting with a 42-year-old man who had never been convicted of a crime but had been on a gang injunction list for years. The man was "guilty of being poor and living in a housing project where other gang members live," Wright said.

The result, some say, is creating an untenable situation.

Jermele Henry and Elvonzo Cromwell, both 31, have been friends since boyhood, but the two don't speak when they see each other at the Jordan Downs housing projects in Watts. They say they are not gangsters but worry police will accuse them of gang activity and arrest them for violating an injunction against the Grape Street Crips.

"I'm scared to come outside," Henry said.