Sign Regulations and the First Amendment
Unfortunately, everyone struggles with the applicability of the First Amendment to the federal Constitution in the context of sign regulations. One of the leading authorities in land use planning law in this country, Daniel Mandelker, has written a publication available online reviewing this area of the law and its impact specifically on business accessory and other on-site signs (as distinguished from billboards).
If you or your municipality are struggling with this area of legal doctrine, I highly recommend this publication. It is clearly written, and emphasizes the important points that need to be made in order to understand how best to avoid constitutional difficulties in the context of sign regulations.