The death of a Florida teenager is sparking new debate on some gun laws across the country.
Volunteer watchman George Zimmerman shot and killed unarmed 17-year-old Trayvon Martin last month in Florida.
Zimmerman claims he shot Martin in self defense, and has not been charged with a crime.
The case has triggered outrage over Florida's "Stand Your Ground" law.
At least 21 other states, including Tennessee, have similar laws which allow citizens to use deadly force when threatened outside the home.
At Randy's Guns and Knives in North Knoxville, personal safety is a strong motivator for customers, and those behind the counter advise new shooters to learn the laws.
"They start asking about the laws and I always recommend they talk to the police department or go through and get their carry permit," said Steven Bowman who works at the store.
Under Tennessee law, a person can fatally shoot to protest life. It's considered "justifiable homicide."
Law enforcement will investigate each case individually.
"They'll review all the evidence, then that evidence is presented to the attorney general, and the AG is actually the one that will make the determination whether or not a charge should be found," said KPD Chief David Rausch.
Then, the burden of proof falls on the shooter, who must prove reasonable force.
"Were you pursuing somebody, or were you being pursued? If they had a weapon, what was it? If they didn't have a weapon, what was the amount of force or aggression that was being used against you," explains Bosch.
In Knoxville, Rausch and Bosch say justifiable homicide is rare. Chief Rausch recalls only one case last year in Knoxville that was deemed justifiable homicide.