The three-page letter sent Sunday by James Sullivan, Abbott’s general counsel, said only the governor has the constitutional authority to delay an execution. Sullivan warned that unless the court rejects the subpoena, “it can be repeated in every capital case, effectively rewriting the Constitution to reassign a power given only to the Governor.”

Texas Governor Greg Abbott said that lawmakers stepped 'out of line' when intervening in the execution of Robert Roberson, who was scheduled to be executed last week