College students around Florida rallied Monday to demand the arrest of a white neighborhood watch captain who shot an unarmed black teen last month, though authorities may be hamstrung by a state law that allows people to defend themselves with deadly force.

Students held rallies on the campus of Florida A&M University in Tallahassee and outside the Seminole County Criminal Justice Center, where prosecutors are reviewing the case to determine if charges should be filed. The students demanded the arrest of 28-year-old George Zimmerman, who authorities say shot 17-year-old Trayvon Martin last month during a confrontation in a gated community in Sanford.

Zimmerman spotted Martin as he was patrolling his neighborhood on a rainy evening last month and called 911 to report a suspicious person. Against the advice of the 911 dispatcher, Zimmerman then followed Martin, who was walking home from a convenience store with a bag of Skittles in his pocket.

Zimmerman's father has said his son is Hispanic and is not racist. Zimmerman has claimed self-defense.

"I don't think a man who exited his vehicle after the 911 dispatcher told him to stay inside the car can claim self-defense," Carl McPhail, a 28-year-old Barry University law school student, said at the Sanford rally.

The 70 protesters at the Sanford rally chanted "What if it was your son?" and held posters saying, "This is not a race issue." Many carried Skittles.

Martin's parents and other advocates have said the shooter would have been arrested had he been black.

"You would think that Sanford is still in the 1800s claiming that this man can call self-defense for shooting an unarmed boy," said restaurant owner Linda Tillman, who also was at the Sanford rally.

The case has garnered national attention, and civil rights activist Al Sharpton and radio host Michael Baisden planned to lead another rally Thursday in Sanford.

But prosecutors may not be able to charge Zimmerman because of changes to state law in 2005. Under the old law, people could face criminal charges for killing someone in self-defense if they did not first try to run away or otherwise avoid the danger.

The changes removed that duty to retreat and gave Floridians, as the law is written, the right "to stand his or her ground and meet force with force, including deadly force," if they felt threatened. The changes also meant people could not be prosecuted in such instances.

Prosecutors can have a hard time making a case if there is no one else around to contradict a person who claims self-defense, said David Hill, a criminal defense attorney in Orlando. Thus far, Sanford police have said there is no evidence to contradict Zimmerman's claims.

"If there is nobody around and you pull a gun, you just say, `Hey, I reasonably believed I was under imminent attack. Hey, sorry. Too bad. But you can't prosecute me,'" Hill said, somewhat tongue-in-cheek.

Gun control advocates said the case is emblematic of permissive gun laws in Florida, which was among the first states to allow residents to carry concealed weapons. Florida was the first state to pass a "Stand Your Ground" law, which has been dubbed a "Shoot First" law by gun control advocates. Currently, about half of all U.S. states have similar laws, said Brian Malte, legislative director of the Brady Campaign, which describes itself as the nation's largest organization dedicated to the prevention of gun violence.

"It's coming to dangerous fruition," Malte said. "There are more states like Florida."