No plans are known yet for the use of nitrogen hypoxia in state executions.
The Alabama Department of Corrections said it does not have a timetable to develop protocol for the method and declined to provide a desciption of how it will be implemented.
The state told a federal judge last week that the construction of a "system" that uses nitrogen gas to carry out death sentences was finished.
Additional safety measures are planned after an expert visited a site to evaluate the system.