Don't they do pretty diligent temperament testing to make sure service dogs won't snap in tense or agitated situations???
Are there cases of real service dogs attacking in public?
No. The dog has to meet certain criteria to begin training. While aggression might be one of them, testing to see if a dog bites is not. It also has to do with the type of service, hearing, seeing eye, diabetic, weed holder or whatever.
Many of those dogs never complete but still during training are certified.
As far as attacking in public or defending itself or its owner I have no idea but would be interesting to see.
Actually, there is no test or certification for a service animal. There are requirements to be met for therapy dogs, which may be what Steven is thinking of. Temperament issues would be something that would wash a service animal from the program. I'm sure there have been instances where a service dog bit, but I don't have any information about that specifically. Most often it's ESAs that you hear about. I would expect that liability would fall on the owner/handler in almost all instances.
This might be of interest:
S. Code of Federal Regulations § 36.202(c)(2):
(2) Exceptions. A public accommodation may ask an individual with a disability to remove a service animal from the premises if:
(i) The animal is out of control and the animal’s handler does not take effective action to control it; or
(ii) The animal is not housebroken.
(3) If an animal is properly excluded. If a public accommodation properly excludes a service animal under § 36.302(c)(2), it shall give the individual with a disability the opportunity to obtain goods, services, and accommodations without having the service animal on the premises.
Also:
https://www.ada.gov/regs2010/service_animal_qa.html
And this bit in particular from the above link -
"The ADA requires that service animals be under the control of the handler at all times ... Under control also means that a service animal should not be allowed to bark repeatedly in a lecture hall, theater, library, or other quiet place. However, if a dog barks just once, or barks because someone has provoked it, this would not mean that the dog is out of control.