The Tennessee Supreme Court has postponed execution dates for four inmates, effectively stopping all executions while the courts decide whether current execution protocols are constitutional.

Tennessee last executed a prisoner in 2009. Since then, legal challenges and problems obtaining lethal injection drugs have stalled new executions.

In 2013 and 2014, the state tried to jump-start the process with a new lethal injection method and the reinstatement of electrocution as a backup. The court set new execution dates for 11 inmates. One inmate died in prison, and the execution dates for the others have been postponed as they approach because of legal challenges to the new methods.

On Friday, the court postponed the last of the scheduled execution dates. It will set new dates after the legal questions are settled.