From The Guardian:
[The] Key West city commission backed the Hemingway Home's claim that the cats are not exhibits and exempted it from a city law prohibiting more than four domestic animals per household.
The exemption, granted last week, states: "The cats reside on the property just as [they] did in the time of Hemingway himself.
"They are not on exhibition in the manner of circus animals. The city commission finds that the family of polydactyl Hemingway cats are indeed animals of historic, social and tourism significance ... an integral part of the history and ambiance of the Hemingway House".