Exactly as Speed said.

The club I belong to has an exclusive 99 year lease of a parcel of State land, and the State has condoned our full use and control of the land. The club has bylaws, of course, one of which is that everyone who operates an RC model there have a current AMA membership, and be either a club member or a guest of a club member (who themself is also a current AMA member). And yes, the State not only condones the AMA member thing, THEY require it in the lease, as it protects THEM (the State) from liability through the AMA insurance.

So, while the one post newb who stated "AMA is not the law anywhere in the USA" may think they're being cute playing with words, at our club having an AMA membership IS the law, and we have STATE permission, in writing, to have the REAL law (the police) escort anyone off of the field who does not comply with ALL of our bylaws, including having a valid AMA membership being one of them.