Whether you can have chickens is not always determined at the local level. In Michigan we have a very strong, state-level Right to Farm Act that was amended in 1999 to protect all commercial farming operations which follow good management practices from local regulations.
I know this sounds contrary to what most people assume, but the wording of the amendment is unambiguous, and both the courts and legal scholars have come to the conclusion that our state Right to Farm law protects chicken operations in residential areas, even when local regulations attempt to restrict those activities.
http://sustainablefarmpolicy.org/the-courts/
http://sustainablefarmpolicy.org/the-scholars/
There is also a remarkable discussion on these issues in this BYC thread:
https://www.backyardchickens.com/t/...farm-law-what-does-it-mean/1220#post_11629602