Tony Carruthers, who was convicted of a 1994 triple murder in Memphis, was set to be put to death at 10 a.m. Thursday.

It is the sixth failed lethal-injection execution in less than 10 years.

Defense attorneys allege the state has used expired or incorrect drugs and improper dosages during lethal injections. Appeals have also challenged a policy allowing executioners to cut into an inmate to find a vein without requiring anesthesia.

The execution was called off after medical personnel could not administer the lethal injection. Lawyers state there have been issues with the procedure for years.

The scheduled execution of Tony Carruthers has been called off, and he will remain on death row for another year.

The U.S. Supreme Court upheld lower court decisions vacating the death sentence of Joseph Clifton Smith, ruling that Alabama cannot execute him due to findings of intellectual disability. The 5-4 decision,