Utah became the only state to allow firing squads for executions Monday when Gov. Gary Herbert signed a law approving the controversial method's use when no lethal injection drugs are available.

Herbert has said he finds the firing squad "a little bit gruesome" but that Utah is a capital punishment state and needs a backup execution method in case a shortage of the drugs persists.

"We regret anyone ever commits the heinous crime of aggravated murder to merit the death penalty, and we prefer to use our primary method of lethal injection when such a sentence is issued," said Herbert spokesman Marty Carpenter. "However, when a jury makes the decision and a judge signs a death warrant, enforcing that lawful decision is the obligation of the executive branch."

The measure's approval is the latest illustration of some states' frustration over bungled executions and the difficulty obtaining the drugs. Utah is one of several states seeking new forms of capital punishment after a botched Oklahoma lethal injection last year.

States have struggled to maintain their drug inventories as European manufacturers opposed to capital punishment refuse to sell the components of lethal injections to U.S. prisons. Texas would have used its last fatal dose this month, but that execution was stayed, and the state has more executions scheduled for April.

The bill's sponsor, Republican Rep. Paul Ray, argued that a team of trained marksmen is faster and more decent form of execution than the drawn-out deaths involved when lethal injections go awry — or even if they go as planned.

Though Utah's next execution is probably a few years away, he said he wanted to settle on a backup method now so authorities will not have to race to find a solution if the drug shortage continues.

Opponents of the measure say firing squads are barbaric, with the American Civil Liberties Union of Utah saying the bill makes the state "look backward and backwoods."

Utah lawmakers stopped offering inmates the choice of firing squad in 2004, saying the method attracted intense media interest and took attention away from victims.

Utah is the only state in the past 40 years use a firing squad to carry out a death sentence, logging three executions by firing squad since the U.S. Supreme Court reinstated the death penalty in 1976.

The last was in 2010, when Ronnie Lee Gardner was put to death by five police officers with .30-caliber Winchester rifles — an event that generated international interest and elicited condemnation from many.

Gardner, who killed a bartender, later shot a lawyer to death and wounded a bailiff during a 1985 courthouse escape attempt. The bailiff's widow, VelDean Kirk, said she supports Utah's efforts to bring back the firing squad.

Ronnie Lee Gardner's brother Randy Gardner has spoken out against the use of a firing squad, saying he doesn't condone his brother's actions but believes the firing squad is barbaric.

The Associated Press