During recent decades, the teaching and discussion of Evidence law have come to focus almost entirely on the topics covered by the Federal Rules of Evidence and their state equivalents. Just as the Federal Rules of Civil Procedure caused teachers and scholars to focus on what they cover, the Federal Rules of Evidence have come to define our understanding of what Evidence law is about.

Any new practice involving communication can pose a challenge to established free speech law. A few such practices are of exceptional value in promoting a clearer understanding of free speech law and, crucially, of the increasingly important deficiencies of even our best free speech theories. The practice of projecting light messages onto targeted property is just such a practice.