I think you mean N2O. NO2 is nasty stuff.
Meh. Their job is to die, not critique the atmosphere.
Personally, I still like the captive bolt gun method. With an option for the victims' families to do the job if they want.
And is anybody else just waiting for Scalia to have enough and write a single paragraph opinion?
"Regarding [plaintiff/defendant]'s argument, duh. Regarding the other side's argument, nobody gives a crap about your imaginative interpretation of long established law. In our opinion, you should settle this amongst yourselves via the time honored tradition of dueling with swords, which shall be provided momentarily so that a decision may be reached without further delay."