The Invention Secrecy Act of 1951 (, codified at ) is a United States federal law that authorizes the government to suppress disclosure of certain inventions for reasons of national security. It first became law as an executive order in 1947, promulgated by the administration of President Harry S. Truman. Full congressional enactment followed in 1951. The exigencies of the Cold War drove its creation and it passed the U.S. Congress relatively quickly once introduced.
The statute empowers selected federal agencies to decide whether a patent application poses a risk and to compel its classification under secrecy orders. In practice, secrecy orders have been imposed not only on inventions affecting military defense but also on those alleged to threaten economic stability, with critics noting that many such restrictions rest on speculative or unproven harms. The law applies broadly to all inventions in the United States for which a patent is filed or granted (). Every patent application is reviewed, and thousands of inventions are manually screened each year. Any federal agency with "classifying powers" can order a restriction under the Act.
Critics, including attorneys and academics, describe the system as lacking oversight and limiting avenues of appeal. Commentators have likened secrecy orders to uncompensated takings under the Fifth Amendment to the United States Constitution, and legal scholars argue that the regime is "inherently unfair" because inventors are automatically denied a quarter of their patent's assessed value while being unable to prove harm. Historians note that officials manage secrecy orders to avoid judicial precedents on the Act's constitutionality.
Other critics contend that secrecy orders chill research, stall economic development, and entrench the military–industrial complex by sidelining independent inventors and dual-use technologies. The statutory rationale in 35 U.S.C. § 181 is that secrecy orders are needed when disclosure "might be detrimental to the national security." Most scholarly commentary has been critical of the regime, though one law review article has argued limited secrecy may be justified in biotechnology patents.
World War I and II background Invention secrecy in the United States can be traced to at least the 1910s, and it accelerated during the 1940s alongside the classified development of nuclear weapons. The precursor to the Invention Secrecy Act was the Espionage Act of 1917. It authorized the Commissioner of Patents to withhold patents during wartime if disclosure might aid the enemy or endanger public safety. Contemporary reports stressed that secrecy orders had to balance national defense with the protection of inventors' rights. The final version of the 1917 World War I–era statute directed the Commissioner of Patents to restrict inventions when:
In 1940, the United States Patent and Trademark Office (USPTO) and the military created the Army and Navy Patent Advisory Board, later renamed the Armed Services Patent Advisory Board, to advise on secrecy determinations. Secrecy orders were intended to last two years beginning July 1, 1940, yet they remained in force for the rest of the war. Through World War II alone, at least 11,000 inventions were submitted for classification review, and other research found that about 8,475 inventions were actually placed under secrecy—roughly 75 percent of all new inventions reviewed during that period, when more than 20,000 total patents were screened.
The Commissioner lifted most secrecy orders in 1945, rescinding more than 6,500 patents, though several hundred remained in place on national security grounds. After 1945, the USPTO rescinded 6,575 wartime secrecy orders, but by 1951 the number of active orders had climbed back to nearly 2,400, reflecting Cold War concerns. By 1951, the backlog of secrecy orders had grown to nearly 2,400 pending applications.
Invention Secrecy Act of 1951 The Invention Secrecy Act (ISA) of 1951 made such patent secrecy permanent, though the order to suppress any invention must be renewed each year, except during periods of declared war or national emergency. The 1951 Act allowed secrecy orders to be renewed annually in peacetime, creating semi-permanent restrictions so long as agencies affirmed a national security need. During wartime or declared national emergencies, secrecy orders were extended automatically until hostilities or emergencies formally ended, plus six months beyond. This gave agencies broad discretion to keep patents restricted. Under 35 U.S.C. § 181, secrecy orders are applied when "publication or disclosure of an invention... might be detrimental to the national security." When the ISA was passed in 1951, the USPTO did not publish pending applications, so the statute did not originally address withholding publication.
The ISA authorized the Commissioner of Patents to flag applications, including those submitted by private inventors, for review by defense agencies and possible restriction. If government officials determine that an idea or invention could pose a threat, it can be restricted from public disclosure under a secrecy order. Any federal government agency, not just those associated with the United States Armed Forces and United States Intelligence Community, may request that any patent be restricted under the ISA if the agency has classification authority.
Under a secrecy order, a patent may be withheld from export, limited in access to defense agencies, or placed under classification. By law, the government is only required to compensate the inventor of a restricted idea for 75 percent of its assessed value, as determined by the restricting agency, and the inventor must demonstrate damages. Congress later revised compensation rules to allow inventors to seek damages caused by secrecy orders without first tendering the invention to the government.
However, inventors find it difficult, if not impossible, to prove they suffered harm under the ISA because they cannot disclose the invention. The 1951 statute also granted inventors limited appeal rights to the Secretary of Commerce and reduced earlier restrictions on foreign filings. If an inventor attempts to file the invention abroad without authorization, it can be deemed legally "abandoned." In Halpern v. United States (1958), the United States Court of Appeals for the Second Circuit rejected the government's position that suits under the ISA could not proceed unless a secrecy order was rescinded, noting that such cases could be tried in camera. Earlier, in Robinson v. United States (1956), the court rejected the argument that a complete administrative denial barred a suit.
In one example, a patent application filed in 1936 remained secret until 2000, when it was finally issued for a cryptograph to manually encode and decode messages, a technology long obsolete by that point. Congress never explicitly justified peacetime secrecy when it passed the 1951 Act, instead relying on Harry Truman's 1950 emergency declaration; hearings in 1980 later noted that peacetime orders lacked a formal legislative rationale. Congress did not provide a rationale for peacetime secrecy, relying on Truman's 1950 emergency proclamation, which extended secrecy orders six months beyond its duration. The Act's peacetime provisions did not truly operate until 1979, because Truman's 1950 emergency declaration kept secrecy orders in force for nearly three decades.
As of 1997, it was reported that five to ten percent of all patents that the American military reviews under the ISA become subject to secrecy orders. In the four-year window of 2013 to 2017, an average of 117 new inventions per year were restricted with secrecy orders. In the same 2013–2017 period, an average of 25 secrecy orders were reportedly rescinded per year. In 2015, the USPTO issued 95 new secrecy orders, about one for every 6,600 patent applications, most tied to inventions created for the military or other federal agencies. In 2017, the Federation of American Scientists reported USPTO statistics that 5,784 patents were restricted under secrecy orders. A total of 5,792 unique patents were under secrecy orders as of 2018. Approximately twelve inventions by private, non-government-affiliated inventors per year are historically classified and made unavailable to develop for the individuals involved.
Through 2012–2020, the United States Patent Office investigated expanding application of the ISA to consider economic impacts on American markets from new inventions, particularly those that might disrupt existing industries. Attempts through 2020 to expand the scope of the ISA in Congress were unsuccessful, attributed to lobbying from groups such as the American Bar Association.
Invention Secrecy Act screening process
Under this Act, defense agencies provide the Patent Office with a classified list of sensitive technologies in the form of the "Patent Security Category Review List" (PSCRL). The decision to classify new inventions is made by "defense agencies" as defined by the President. These agencies include the Pentagon, the National Security Agency (NSA), the United States Department of Justice, and the United States Department of Homeland Security. The law applies to all inventions created in the United States, regardless of their nature or nationality of the creators, though the "vast majority" of inventions have no legal or financial stake from the government. The ISA applies only to inventions created in the United States; inventions made abroad fall outside its scope. All patents filed within the country are required to be screened for the ISA.
Each year, tens of thousands of new inventions and patent applications were manually reviewed to determine whether they should be hidden from the public. When the government had no property interest in an invention, the United States Patent and Trademark Office (USPTO) played a larger role in secrecy decisions. Orders were determined through a two-stage process, first at the Patent Office and then at a defense agency.
USPTO's Group 220 conducted secrecy review of all applications and forwarded flagged ones to defense agencies for opinion. USPTO examiners relied on the Armed Services Patent Advisory Board's Patent Security Category Review List, which contained 21 invention categories of security interest to agencies such as the United States Army, Navy, Air Force, the United States Atomic Energy Commission (AEC), NASA, and the NSA. Roughly three percent of all patent applications fell into these areas.
If agencies determined that disclosure would harm national security, they notified the Commissioner, who was required to order secrecy. Of the thousands reviewed by defense agencies, five to ten percent were subjected to secrecy orders. Agency heads (or delegates) needed only to determine detriment to national security; upon notice, the Commissioner had to order secrecy and withhold publication and grant of the patent. The Commissioner of Patents was legally compelled to comply.