in a word, yes depending on your local laws.
if your dog bites unprovoked, etc you could face stronger charges...its kinda like if a professional cage fighter or boxer gets into a bar fight, depending on where you live he could face stronger charges, possibly including assault with a deadly weapon(fists) because he is trained.
also as far as liability goes, check your laws. in general, if an intruder comes into your home, you are in the clear. some places the criminal has more rights than they should. in some towns. you could end up in court if you send your dog into your home to clear it, if you are in the streets and you get assaulted and your dog bites, in the car, it all depends. i know here i believe if you have opportunity to leave without the criminal knowing(aka, you come home and see your door open or windows broken, the law wantsd you to turn and leave and call the police, not go in. if you do and shoot the guy(or send the dog) it might not turn out well legally