The paper discusses five key principles which guide the teaching of legal visualization by Friedrich Lachmayer. First, legal visualization is a kind of a nontextual notation. Second, legal visualization is a bridge from law to technology. Third, legal informatics supplements legal dogmatics to form a new conception of legal science. Fourth, abstraction is a guide from image via structure toward categories. Five, Structural Legal Visualization (SLV) is proposed as a method in legal informatics.