A death row inmate slated to become the first person to be put to death by nitrogen gas in Louisiana is seeking to halt the execution, citing constitutional concerns over the controversial killing method.

Louisiana is scheduled to execute a man with nitrogen gas on March 18. Arkansas lawmakers are seeking to introduce nitrogen there after an eight-year pause in executions.

A death row inmate in Louisiana who is scheduled to become the first person in the state to be executed using nitrogen gas has asked for his capital punishment to be carried out using a more “humane” method.