Uncloaking Stealth Prior Art

Can you guess what a press release, a contract manufacturer's quote, an offer to sell a new product, a trade show display, a grant application, and a regulatory submission may all have in common when it comes to patenting an invention? They can all be forms of stealth prior art that could prevent patent protection. Stealth prior art is prior art that does not attract attention.

Consider the story of Wayne Pfaff, who fi led an application for a patent on a computer chip socket on April 19, 1982. The U.S. Patent and Trademark Offi ce duly examined the application and issued Pfaff a patent on his application in January 1985. Pfaff later fi led a patent infringement lawsuit against Wells Electronics, a manufacturer of a competing socket. Wells Electronics defended itself on the basis that Pfaff's patent was invalid, and succeeded in invalidating Pfaff's patent based on stealth prior art. In Pfaff's case, it was his own engineering drawings and his sale of sockets to