Trade secret law is the oldest form of IP protection, and already in Roman times the law afforded relief against a person who induced another’s employee (slave) to divulge secrets relating to the master’s commercial affairs. Trade secrecy was practiced extensively in the European guilds in the Middle Ages and beyond. Modern trade secret law evolved in England in the early 19th century — in response to the growing accumulation of technology and know-how and the increased mobility of employees. Recognized in U.S. by the middle of the 19th century, Peabody v. Norfolk (98 Mass. 452 (Mass. 1868)) held that a secret manufacturing process is property, protectable against misappropriation; secrecy obligation for an employee outlasts the term of employment; a trade secret can be disclosed confidentially to others who need to practice it and a recipient can be enjoined from using a misappropriated trade secret. This decision anticipates the characteristics of our present trade secret system and by the end of the 19th century the principal features of contemporary trade secret law were well established. It is interesting to note that Henry Perritt believes that indeed trade secrets are “the oldest form of IP protection” and that “patent law was developed as a way of protecting trade secrets without requiring them to be kept secret and thereby discouraging wider use of useful information.” (Henry H. Perritt Jr., Trade Secrets 1-1, 3-7 (Practising Law Institute 2d ed. 2006)) That makes patents supplements to trade secrets and not trade secrets supplements to patents as is commonly assumed.