This issue has already been tried in the federal court system, which regulates Constitutional protection. The first amendment and the takings provision of the fifth amendment are involved. Public art, when involving a prescribed subject, is prior restraint when federal funds are in the funding end of things. Public art is a taking when it is leveraged by government in terms of permitting and zoning. Only "great" art enjoys the kind of protections Wyland and Meyer allege illustration or stencil stuff also has. Not so, inherently and not so as per cases already heard. The Center Art Gallery cases, thats Blalog, go into detail. The "great" art case slips my mind and I'm too lazy to look for it. Another case is Saint Johns river management district, aka Koontz.