NASHVILLE, Tenn. (AP) — If prison officials in Tennessee run out of the drugs used to carry out a lethal injection on a death row inmate, they can now use the electric chair.

Republican Gov. Bill Haslam signed a bill into law Thursday allowing the state to electrocute condemned inmates.

Lethal injection drugs are becoming more and more scarce following a European-led boycott of drug sales for executions.

Groups that oppose executions say they expect legal challenges to arise.