http://dogobedienceadvice.com/which_dog_breeds_are_most_aggressive.php
1 Dachshund (around one in twelve have turned on and bitten or tried to bite their owners)
2 Chihuahua
3 Jack Russell terrier
4 Akita
5 Australian cattle dog
6 Pit bull
7 Beagle
8 English springer spaniel
9 Border collie
10 German shepherd.
Breed specific legislation is getting ridiculous. It's HOW you raise a dog and their parentage that can cause aggression, not whether or not a dog is a specific breed. To me, that's like saying that just because someone is a certain race, they deserve to have different laws because they might be more likely to do something. It makes me sick that because boxers, pits, and rottweilers look scary, they're branded as dangerous and aggressive. Look at the top three dogs, for crying out loud - they're no bigger than some cats!
Some cities say that if your dog passes obedience/personality tests and receives a certificate, you can be exempt from certain rules. Tell your sister to check into this. I don't see how the chipping will help if a dog is attacking you, but if it would get the city to be quiet and leave her alone, I would do that as well. However, the city she's in made a mistake in the wording of their laws - if they are wanting to control AGGRESSIVE breeds, they better be monitoring the chihuahuas, dachshunds, and jacks russell terriers as much as the pits and boxers!
The story I read doesn't specifically names boxers as an aggressive breed. Are you concerned about her dog be labeled as a pit? If so, she should look into getting a DNA test done to verify that her dog is a boxer, not a pit, or at the very least, get a record from her veterinarian. My husband and I have a record from the shelter where we got Chase, who is obviously a pitbull/American bulldog, that says he is a lab/boxer/shepherd mix just in case we run into a case like this. She should get whatever documentation she can from whatever breeder/shelter she got her dog from. Unless they specifically name a boxer, as far as I'm concerned, the law doesn't apply to her.