Umm, how about locking up your guns even if your child is not a sleepwalker?
Or (gasp) not keeping guns in your house?
The Canadian case was R. v. Parks, which went all the way to the Supreme Court of Canada. The Court held that on the facts of this particular case, the sleepwalking was a form of non-insane automatism, and therefore a complete defence to the two murder charges.
Now now, sjgouldrocks, you don’t want this thread to get thrown into Great Debates, do ya?
I think that sjgouldrocks forgot to put in a winkie smilie ( 
) to indicate that he was giving a completely off the wall, humourous suggestion, that people shouldn’t take seriously.