"Don't Hide The Ball" - Best Mode in the US Patent System


I am pleased to join you from south of the border. My work has been focussed in the United States. Intellectual property laws are very powerful and important today. Yet they are but part of the larger body of law in any country. They are also part of a developing fabric of international commercial regulation. I hope that discussions will focus on why one should or should not create personal or exclusive rights in these fields.

To open this conversation, I’ve chosen to focus on a facet of United States patent law, called the “best mode” requirement. This obscure doctrine sheds light on the process and purposes of United States patent law. It also provides a glimpse of how legislators, judges, and attorneys view the inventive process, especially in its commercial environment.

What is “best mode.“ In the US, a patent applicant must disclose all he or she knows about how an invention works. Subject to Supreme Court rulings, the United States has one appellate court, the Federal Circuit, to resolve patent law questions. The Federal Circuit has summed up the disclosure requirements: “To constitute adequate disclosure …, a patent specification must set forth both the manner and process of making and using the invention (the enablement requirement) and the best mode contemplated by the inventor of carrying out the invention (the best mode requirement).” Spectra-Physics, Inc. v. Coherent, Inc., 827 F.2d 1524, 1532 (Fed. Cir. 1987). In short, the  applicant must describe what to do and how best to do it.

Judge Giles Rich made a major impact on the development of United States patent law. He thought the purpose best mode rule was to assure full disclosure of an invention. “There always exists, on the part of some people, a selfish desire to obtain patent protection without making a full disclosure, which the law, in the public interest, must guard against. Hence section 112 calls for description in ‘full, clear, concise, and exact terms’ and the ‘best mode’ requirement does not permit an inventor to disclose only what he knows to be his second-best embodiment, retaining the best for himself.” See Application of Nelson, 280 F.2d 172 (Cust. & Pat. App. 1967).

The “best mode” requirement is unique to United States patent law. Even in the United States only certain attorneys, judges and law students cramming for a patent exam know anything about it. Joseph Root is an attorney who has spent a lifetime in patent law. In a recent 80 page article he observed, “Best mode problems are like falling asteroids… when they do strike, big problems follow.” Joseph E. Root, Ducking the Asteroid…, 36 AIPLA Q.J. 455, 457 (2008).

In September 2011, Congress enacted the “America Invents Act” (AIA). It is a packet of changes to the 1952 United States patent law that goes into effect in September 2012. As part of an effort to “harmonize” United States law with that of other nations, the AIA modified the best mode requirement. The amended law retains the requirement that one disclose the best mode, however, failure to do so will no longer render a patent invalid or unenforceable.

It is tempting say the new rule requires one to disclose, but eliminates consequences for failure to do so. However, that summary is misleading. The fundamental rule remains: Disclose the invention! The law continues to require one to disclose exactly how an invention works. Failure to do so will render a patent invalid. Furthermore, concealing relevant information from the Patent Office will also invalidate a patent.

Don’t hide the ball. Most inventions are improvements of something that came before–engines, suspension systems, antibiotics, software, and on and on. Thus, most disclosures amount to describing a better way of doing something. Better and best overlap. The Federal Circuit has repeatedly emphasized that describing how to do something and the best way of doing it converge: “The focus of the best mode requirement, as it was with the enablement requirement, is on the claimed invention. Thus, before determining whether there is evidence of concealment, the scope of the invention must be delimited.” Chemcast Corp. v. Arco Industries Corp., 913 F.2d 923, 927 (Fed. Cir. 1990).

The bottom line for practitioners and applicants remains the same before and after the effective date of the AIA. When applying for a patent, one must disclose what one knows about the invention. Candor is the essence of the patent system. The constitutional goal of the US patent system is to expand knowledge and to provide useful new inventions to the public. Attorney Root summed the matter up: “Never appear to hide the ball: Always disclose specially made materials, inventor choices based on test results, and essential process steps.”

The new rules clearly change how courts handle claims that a patent is invalid. However, as the Federal Circuit emphasized, best mode and enablement overlap. Thus, much of the same evidence will come into a trial before and after the effective date. Failure to include information can be found to be “hiding the ball” from the Patent Office. In some cases, it may amount to failure to disclose fully the enablement.


Howard C. Anawalt is a United States attorney, law professor, and writer. His latest book is Idea Rights: A Guide to Intellectual Property (Carolina Academic Press 2011). He discusses the subject in an Authors@Goggle presentation, http://www.youtube.com/watch?v=mU46YcYAnB

  1. Hi Professor Anawalt,

    Thank you for the interesting post. Your discussion of best mode and disclosure comes at an interesting time in Canada as our Supreme Court will be hearing a disclosure argument in a few months regarding Viagra. In a patent covering Viagra Pfizer claimed 260 quintillion compounds but at the time the patent was filed they knew of only one (sildenafil) that was effective in their tests for treating ED. Despite this knowledge, the patent was cleverly drafted so as to never actually disclose that the only known active compound at the time was sildenafil. One of the main arguments before the Supreme Court is that Pfizer was required to clearly disclose the identity of sildenafil. Pfizer appears to contend that because the patent contains an independent claim for sildenafil, despite not specifically identifying sildenafil as the only known effective compound, they have met the disclosure requirement. It will be interesting to see how Canada’s highest court deals with the disclosure requirement and if they draw on American jurisprudence for guidance.

  2. Professor Anawalt’s comment in his interesting post includes the statement that the best mode requirement is “unique” to U.S. patent law. This is not quite true. The best mode requirement was imposed by English judges from the late 18th century. They required the “most beneficial” mode of working the invention that the inventor then knew to be stated as part of the inventor’s duty of full disclosure (Boville v. Moore (1816), 1 Carpmael’s Pat. Cas. 320, 339). See the 2nd edition of my Intellectual Property Law book at p. 344: ‘If the inventor had made a patented article “with cheaper materials than those which he has enumerated [in his specification], although the latter will answer the purpose equally well, the patent is void, because he does not put the public in possession of his invention, or enable them to derive the same benefit which he himself does”’ citing Turner v. Winter (1787), 99 E.R. 1274 (K.B.), etc. I think this obligation carried over into Canadian patent law before and after Confederation, despite puzzling 1935 amendments to the Canadian patent law drawn from equally puzzling ones in US law. Many countries continue to have such a requirement in their law, either explicitly or implicitly as part of the full disclosure obligation. The UK had a statutory version of it too until it joined the European Patent Convention, which allows second-best disclosure. We shall see what the Canadian position is when the Supreme Court decides the Viagra patent case, referred to by Sean in his post.

  3. Touché.
    I suspect nothing is unique in our systems. It is an unusual requirement I appreciate Professor Vaver’s correction and will note it when appropriate. I think requiring disclosure of best mode is basically a good idea, as patent is a privilege. The Boville case, which he cites, well observes its value. After all, one is excluding all others from doing something. (The congressional report stated, “Many have argued in recent years that the best mode requirement, which is unique to American patent law, is counter- productive.” H.R. REP. 112-98(I), H.R. REP. 112-98, H.R. Rep. No. 98(I), 112TH Cong., 1ST Sess. 2011, page 52.)
    In any event, best mode remains alive in United States patent law. How well it does to reinforce full disclosure remains to be seen.

    Howie Anawalt

Comments are closed.