“That’s not cool in my book,” Art Andersen, 44, said as he nursed a Coors Light at Sam’s Sports Bar and Grill near Vanderbilt University. “It opens the door to trouble. It’s giving you the right to be Wyatt Earp.”

Tennessee is one of four states, along with Arizona, Georgia and Virginia, that recently enacted laws explicitly allowing loaded guns in bars. (Eighteen other states allow weapons in restaurants that serve alcohol.) The new measures in Tennessee and the three other states come after two landmark Supreme Court rulings that citizens have an individual right  not just in connection with a well-regulated militia  to keep a loaded handgun for home defense.

Experts say these laws represent the latest wave in the country’s gun debate, as the gun lobby seeks, state by state, to expand the realm of guns in everyday life.

The rulings, which overturned handgun bans in Washington and Chicago, have strengthened the stance of gun rights advocates nationwide. More than 250 lawsuits now challenge various gun laws, and Gov. Rick Perry of Texas, a Republican, called for guns to be made legal on campuses after a shooting last week at the University of Texas, Austin, arguing that armed bystanders might have stopped the gunman.

The new laws have also brought to light the status of 20 other states  New York, New Jersey and Massachusetts among them  that do not address the question, appearing by default to allow those with permits to carry guns into establishments that serve alcohol, according to the Legal Community Against Violence, a nonprofit group that promotes gun control and tracks state gun laws.