Lawyers for the first inmate scheduled to be put to death with nitrogen gas argued in Monday court filings that Alabama is seeking to make him the “test case” for an experimental execution method and asked a federal judge to the block the January execution. Attorneys for Kenneth Eugene Smith, 58, filed an amended lawsuit challenging the proposed new execution method as a potential violation of the Constitution's ban on cruel and unusual punishment. Alabama Gov. Kay Ivey this month set a Jan. 25 execution date for Smith using nitrogen hypoxia, an execution method that is authorized in Alabama, Mississippi and Oklahoma but that has never been used to put an inmate to death.