There were 5,023 invention secrecy orders in effect at the end of FY 2008, up slightly from last year’s total of 5,002.
Under the Invention Secrecy Act of 1951, secrecy orders are applied by government agencies to patent applications that may be “detrimental to national security.” The patent is withheld, and the invention described in the application is subject to various degrees of restriction, depending on its sensitivity, from export controls to national security classification.
Last year, 68 new secrecy orders were imposed, while 47 were rescinded, according to statistics released by the U.S. Patent and Trademark Office in response to a Freedom of Information Act request from the Federation of American Scientists.
The specific nature of the currently restricted inventions is, of course, not published. But it is possible to get information about dozens of patent applications that were formerly subject to secrecy orders that were later rescinded.
A list of secrecy orders rescinded in 2005-2006 (pdf), by application number, was released in response to a FOIA request from researcher Michael Ravnitzky.
A description of each formerly restricted application can be found by searching the application number on the Patent Office web site. Thus, the first invention on the list was described as a “rocket engine chamber with layered internal wall channels.”