Every time police Sergeant Joseph Hubbard stops a speeder or serves a search warrant, he says he worries suspects assume they can open fire -- without breaking the law.

Hubbard, a 17-year veteran of the Police Department in Jeffersonville, Ind., says his apprehension stems from a state law approved this year that allows residents to use deadly force in response to the "unlawful intrusion" by a "public servant" to protect themselves and others, or their property.

"If I pull over a car and I walk up to it and the guy shoots me, he's going to say, 'Well, he was trying to illegally enter my property,'$?" said Hubbard, 40, who is president of the Jeffersonville Fraternal Order of Police Lodge 100. "Somebody is going get away with killing a cop because of this law."

Indiana is the first U.S. state to specifically allow force against officers, according to the Association of Prosecuting Attorneys in Washington, which represents and supports prosecutors. The National Rifle Association pushed for the law, saying an unfavorable court decision made the need clear and that it would allow homeowners to defend themselves during a violent, unjustified attack. Police lobbied against it.

The NRA, a membership group that says it's widely recognized as a "major political force" and as the country's "foremost defender" of Second Amendment rights, has worked to spread permissive gun laws around the country. Among them is the Stand Your Ground self-defense measure in Florida, which generated nationwide controversy after the Feb. 26 shooting of Trayvon Martin, an unarmed Florida teenager.

Castle Doctrine amendedAsked about the Indiana law, Andrew Arulanandam, a spokesman for the Fairfax, Va.,-based NRA, said he would look into the matter. He didn't return subsequent calls.

The measure was approved by the Republican-controlled legislature and signed by Republican Gov. Mitch Daniels in March. It amended a 2006 so-called Castle Doctrine bill that allows deadly force to stop illegal entry into a home or car.

The law describes the ability to use force to "protect the person or a third person from what the person reasonably believes to be the imminent use of unlawful force."

Republican State Sen. R. Michael Young, the bill's author, said there haven't been any cases in which suspects have used the law to justify shooting police.

He said "public servant" was added to clarify the law after a state Supreme Court ruling last year that "there is no right to reasonably resist unlawful entry by police officers." The case was based on a man charged with assaulting an officer during a domestic-violence call.

Young cited a hypothetical situation of a homeowner returning to see an officer raping his daughter or wife. Under the court's ruling, the homeowner could not touch the officer and only file a lawsuit later, he said. Young said he devised the idea for the law after the court ruling.

"There are bad legislators," Young said. "There are bad clergy, bad doctors, bad teachers, and it's these officers that we're concerned about that when they act outside their scope and duty that the individual ought to have a right to protect themselves."

Supporters of the bill tried to accommodate police by adding specific requirements that might justify force, and by replacing "law enforcement officer" in the original version with "public servant," said Republican State Rep. Jud McMillin, the Indiana House sponsor.

Preventing injuryThe measure requires those using force to "reasonably believe" a law-enforcement officer is acting illegally and that it's needed to prevent "serious bodily injury," Daniels said in a statement when he signed the law.

"In the real world, there will almost never be a situation in which these extremely narrow conditions are met," Daniels said. "This law is not an invitation to use violence or force against law enforcement officers."

Jane Jankowski, a spokeswoman for Daniels, referred questions about the measure to that statement.

Opponents see a potential for mistakes and abuse.

It's not clear under the law whether an officer acting in good faith could be legally shot for mistakenly kicking down the wrong door to serve a warrant, said State Sen. Tim Lanane, the assistant Democratic leader and an attorney.

"It's a risky proposition that we set up here," Lanane said.

Those who are intoxicated or emotional can't decide whether police are acting legally, and suspects may assume they have the right to attack officers, said Tim Downs, president of the Indiana State Fraternal Order of Police. The law didn't need to be changed because there isn't an epidemic of rogue police in Indiana, he said.

"It's just a recipe for disaster," said Downs, chief of the Lake County police in northwest Indiana. "It just puts a bounty on our heads."

Downs said he canceled his NRA membership after the organization pressed for the Indiana legislation.

The NRA helped get the measure through the legislature and encouraged its members to contact lawmakers and Daniels.

The organization's Indiana lobbyist attended all the Legislative committee hearings, said State Rep. Linda Lawson, the Democratic floor leader and a former police officer.

Lawmakers respond to the NRA because the group brings political support, Lawson said.

The legislation reversed an "activist court decision," and "restores self-defense laws to what they were," the NRA said on its legislative website.

In Clay County, Ind., outside Terre Haute, the Sheriff's Department changed its procedures because of the law. Detectives in plain clothes and unmarked cars now must be accompanied by a uniformed officer on calls to homes, Sheriff Michael Heaton said.

"I'm not worried about the law-abiding citizens," said Heaton, who also is president of the Indiana Sheriff's Association. "It's the ones that really don't understand the law and they just think, 'Cop shows up at my door, I can do whatever I want to him.'$?"

Hubbard, the officer in Jeffersonville, in southeastern Indiana, said the law causes him to second-guess himself. He serves on the department's patrol division and is a member of its special weapons and tactics unit. The department serves "thousand" of warrants a year, he said.

"It puts doubt in your mind," said Hubbard, who served in the Marine Corps before joining the department. "And hesitation in our job can mean somebody gets hurt or killed."

Hubbard said he hasn't changed his approach to his job or noticed a difference in how civilians he encounters are behaving.

The law has changed Hubbard's view of the NRA.

He said he has been "a proud member of the NRA for years," and while he's still a member and NRA firearms instructor, "the day I found out the NRA was pushing behind this bill was the day I became a not-so-happy NRA member."

-- Mark Niquette, Bloomberg News