There is no certification required, but it's good to have a letter or even a script from your medical doctor or psychologist regarding a need for the service dog or for the emotional support animal.
Actually there are no separate State laws, legally. All must abide by the ADA. The two questions that can be asked are : is the a service dog? What two or three tasks does it do for you that you can't do for yourself? Of course, this doesn't apply when the dog is in training. A service dog in training is allowed anywhere a trained one is allowed. (Unfortunately this does not include places of worship, where they can refuse your presence with the service dog! I no longer attend any worship services since I have no place to go.)
It does greatly hurt those of us who use and need a service dog when others lie about their pet just because they want to drag it along. The two questions usually ferret those liars out.
I have had to educate many business owners, especially restaurants, by calling the police to inform. I do carry ID for the dog as I have the ADA law printed on the back. hahaha Received many a free meal...even after leaving having a letter mailed to me for same...they don't want to be sued!
Excuses are not accepted. If someone is allergic or afraid, well, there's therapy for that and they need to address their own issues and not impose upon the rest of us who are.
Just my 2 cents. ((I have more to spend btw))
Jean