4 Rules

RULE II: Never let the muzzle cover anything you are not willing to destroy.

Uncle has also pointed out in the past that the 4 Rules are set up in such a way so that for something bad to happen, you have to be breaking at least two of them simultaneously.  In the linked case, Rule 1 (all guns are always loaded) was broken.

Sort of as an aside, this is why you don’t practice “clearing your house” with your wife playing the badguy.  No matter which way you look at this, it’s a tragedy, and I agree with Robb that the husband should be charged with manslaughter.