Many thanks to Danianne Mizzy of the University of Pennsylvania for sharing this NPR story on the role of patents in the development of the atomic bomb in the 1940s.
Many of the scientists (and their universities) involved in the Manahattan Project, including Edward Teller, Enrico Fermi, Leo Szilard, Ernest O. Lawrence and John Von Neumann, were keen to obtain patents for their work because they believed that atomic energy would become a lucrative commericial opportunity. Some scientists predicted that atomic energy would be used for hundreds of applications ranging from generating electricity and powering ships and airplanes, to massive demolition charges for mining and construction.
The U.S. government, concerned that atomic technology would fall into the wrong hands, quickly took steps to block these aspirations. In 1946 Congress enacted legislation prohibiting the patenting of atomic weapons. Shortly thereafter it passed invention secrecy laws that required the Patent Office to issue secrecy orders on all applications for sensitive technology, atomic or otherwise, that could impact national security. These applications are kept secret until the government decides that the information they contain no longer poses a danger.
One of the patents (#6,761,862) profiled in the NPR story was issued sixty years after it was filed. Two of the longest pending applications were issued in 2000 (patent #s 6,097,812 and 6,130,946) to William Friedman. Friedman was a cryptographer who worked for the Army and National Security Administration from the 1920s to the 1950s. In the early 1930s he filed patent applications for electro-mechanical cipher machines for encoding and decoding secret messages.
According to the Federation of American Scientists, there are currently 5,002 secrecy orders in effect. In FY 2007 the USPTO imposed 128 new orders and rescinded 68. According to the USPTO, more than 3,000 of these secret cases have been approved for allowance.