Bring back Jack Ketch.
OK, I had to find out who that was...sounds like the man for the job
in this case!
Jack Ketch
http://en.wikipedia.org/wiki/Jack_Ketch
I like the idea of bringing back the guillotine. Swift, certain, and with the right prep you can then harvest organs for transplant — something you can’t do with AC current or gas.
But absent a homicide, capital punishment is unlikely. I’d suggest a smaller guillotine, one that starts its drop around the navel and finishes its transit around the upper thigh.