Jeff mentions the situation in England where defending yourself or your family will likely get you a stiffer penalty than the criminal who attacked you.  This naturally could lead to situations where citizens just kill the bastards and hide the bodies.  Why call it in if you know your life is ruined, regardless of justification?

In a similar vein, the same idea when related to certain “protected” wildlife in certain states (*cough* California *cough*) has led to the pithy phrase “shoot, shovel, and shut up.” 

Unfortunately, the British don’t have many guns (or at least the law abiding citizens don’t), so perhaps it will be “stab/bludgeon, shovel,and shut up”, but it’s a logical outgrowth of an intolerable situation in regards to self defense.