According to the news, lethal injection is considered to be

The Supreme Court has upheld lethal injection as a method of execution. Justices rule 7 to 2 this morning rejecting a constitutional challenge brought by a case in Kentucky. At issue was whether the most common method of capital punishment used by 35 states can cause excruciating pain for death row inmates, violating the constitution’s ban on cruel and unusual punishment. The ruling will likely allow states to resume executions which had been on hold pending the Supreme Court decision. Virginia’s governor has already lifted his state’s moratorium on executions.