Before Brenden Leydon came along, the Town of Greenwich, Connecticut had an ordinance that banned out-of-towners from its beach. Leydon, however, wanted to jog down the Greenwich Point Beach and, believing he had a right to do so, filed a lawsuit against the Town. His right to jog on the beach, he first argued, was rooted in the public trust doctrine, an ancient law developed by a Roman Emperor who may have believed, as Leydon did, that something special about the seashore made it a place that everyone should be able to access. Leydon next argued, under a more modern and familiar doctrine, that his right to free speech and expression was violated when he was prevented from accessing the beach and “exchanging ideas and information with other...