Client/tenant with service dogs question

[Daniel Bryant]

I have a client that rents out a commercial suite from me here in NYC for over a year. Yesterday he came with a pet dog who’s about a month old into my building and into his room… when I told him that we cannot have pets in the building he said that it’s not a pet, it’s a service dog that he MUST have because of his anxiety issues and that I’m not legally allowed to question him about it nor deny him access..

I’ve asked him for documentations stating this and he said I’m not allowed to ask for it either…

What am I supposed to do here in this situation