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“Best Mode” of the Whole Invention Must Be Described


Sunstein | Winning IP View more articles

The Federal Circuit recently ruled two patents invalid for failing to satisfy the “best mode” requirement. In doing so, the court rejected the patentee’s argument that the best mode need be disclosed only for the “innovative aspects” of the invention. Instead, the best mode must be disclosed for the entire invention as claimed.

The Federal Circuit further held that the patentee’s best mode violation was done with sufficient intent to warrant finding the two patents unenforceable for inequitable conduct. The court’s opinion, in Ajinomoto Co. v. International Trade Commission, upheld a ruling of the ITC.

The Statute

The first paragraph of 35 U.S.C. § 112 requires the patent specification to “set forth the best mode contemplated by the inventor of carrying out his invention.” This best mode requirement is separate from the same paragraph’s “enablement” requirement, which calls for describing an invention in such clear and exact terms that someone of ordinary skill is enabled to practice the claimed methods without undue experimentation.

While the patents in Ajinomoto met the enablement standard, the question was whether the inventors had disclosed what they thought was the “best mode” of practicing these claimed methods.

Facts of the Case

Ajinomoto Co. had developed a way of making the amino acid L-lysine using a bacterium having a mutant gene. The patents at issue had (i) claims directed to the mutated DNA sequence, (ii) claims directed to the microorganisms having the mutated DNA sequence, and (iii) claims directed to methods of using these microorganisms to produce L-lysine. Only the method claims were asserted in the ITC proceeding.

In the ITC proceeding, it was shown that the inventors had developed several strains of bacteria and determined that one of these strains was the best candidate for receiving the mutant gene and achieving the highest production of L-lysine. Accordingly, the inventors inserted the mutant gene into this preferred strain and then used this strain to actually produce L-lysine.

However, the patent application did not describe this particular bacteria strain, instead describing a different, less preferred strain—a strain into which the inventors had apparently never even inserted the mutant gene. In addition, Ajinomoto deposited a bacteria strain other than the preferred strain in an international depository. Furthermore, it was found that the inventors included in the patent application fictitious data associated with the non-preferred strain.

The accused infringer argued that the patents failed to satisfy the best mode requirement. Ajinomoto countered that the “innovative aspect” of the claimed invention was the mutant gene, and since the best mode of mutant gene was disclosed in the patent it had met the legal requirement.

The Federal Circuit, like the ITC below, rejected this argument, ruling that the best mode must be disclosed for the invention as claimed. Since the claims at issue were directed to methods of using the entire microorganism containing the mutant gene, the preferred microorganism must be disclosed. The court explained:

Infringement requires all claim limitations to be present, not just those that distinguish the claim from the prior art. So too with the best mode requirement, which applies to the invention claimed, with all its limitations, not just the novel ones. Ajinomoto claimed the right to exclude competitors from practicing a method of producing lysine by cultivating a bacterium with an ldc or dapA mutation. Thus, … the best mode requirement obligated Ajinomoto to disclose its best bacterium for carrying out those inventions.

The Federal Circuit distinguished its 1987 opinion in Christianson, which involved patents for rifle parts. There, the best mode did not require the production details for a particular weapon, the M-16, because the claims did not recite an entire rifle; instead, the claims were directed to the use of the rifle parts in any rifle. Although Ajinomoto argued that its invention was analogous—because the ldc and dapAmutations can be used in any microorganism—the Federal Circuit disagreed:

Ajinomoto’s asserted claims, in contrast, encompass more than the isolated ldc or dapA mutations, analogous to the rifle parts inChristianson; the claims encompass cultivating a bacterium containing such mutations, analogous to the weapon containing the rifle parts inChristianson. Thus, Ajinomoto’s undisputed preference for cultivating a particular bacterium constituted a best mode of carrying out the claimed invention, regardless whether the mutations could be used in other bacteria, and thus that preferred bacterium had to be disclosed.

Ajinomoto’s method claims were consequently found invalid.The claims of the patent directed to the mutated DNA sequence by itself—claims that were not a part of the ITC proceeding—may not be invalid for this failure to comply with the best mode requirement, because those claims do not include the microorganism. However, because the ITC and Federal Circuit found that the failure of the inventors to disclose the best mode of the microorganism was done intentionally, the entire patent is deemed unenforceable.

The Lessons

The best mode requirement, like the enablement requirement, is part of the government’s bargain with the inventor. In exchange for a monopoly on an invention for a period of years, the inventor must disclose to the public how it can best take advantage of the invention after the monopoly expires. If patentees withhold the most practical or effective mode of practicing their invention, the “useful arts” are not advanced as much.

Patents are not often invalidated by the best mode defense. Nevertheless, failing to comply with the best mode requirement can lead to very serious consequences, as the Ajinomoto decision shows. Although recent legislative proposals for patent reform could restrict or effectively eliminate the best mode defense, care must be taken to disclose the inventor’s best mode unless and until such legislation is passed.

Problems can occur when inventors are located in foreign countries. The overwhelming majority of countries do not have a best mode requirement, and if the patent application was first drafted by a foreign patent agent who is unfamiliar with U.S. requirements, the best mode may be left out of the application.

A best mode problem cannot be cured by adding new matter to a patent or application. In some cases, a continuation-in-part application can be filed that discloses the best mode, but the earlier priority date may not then be available, and the later priority date could be fatal to patentability because of intervening prior art. (Noting that its later-filed patent contained additional disclosure, Ajinomoto argued that this patent complied with the best mode requirement after all. However, the Federal Circuit dismissed this argument because Ajinomoto had relied on the earlier priority date for both patents—to get behind possible prior art—and it was too late to make this argument for the first time on appeal.)

It is important to note that every case is decided on its own facts. Often it is not clear how much detail is required for an “adequate description” of the best mode. For example, in a dispute between two pharmaceutical companies, the Federal Circuit found Amgen to have satisfied the best mode even though it had not deposited any microorganism (as opposed to Ajinomoto, which deposited a microorganism that was not preferred), and even though the court recognized that Amgen’s cell line could never be duplicated exactly.

The Federal Circuit ruled in that 1991 case that exact duplication is not necessary:

[W]hen . . . the organism is created by insertion of genetic material into a cell obtained from generally available sources, then all that is required is a description of the best mode and an adequate description of the means of carrying out the invention, not deposit of the cells. If the cells can be prepared without undue experimentation from known materials, based on the description in the patent specification, a deposit is not required.

Although the court ruled that a deposit was not necessary in the Amgen case, a deposit may be necessary in other cases.

The Federal Circuit has also established in a 2001 decision that a preferred mode for accomplishing a “routine detail” need not be disclosed, “because one skilled in the art is aware of alternative means for accomplishing the routine detail that would still produce the best mode of the claimed invention.”

Of course, it is often not clear whether a detail is a “routine detail.” In a 1988 ruling, the Federal Circuit faulted an inventor for failing to disclose a surface treatment that was known in the art. The inventor knew that the specific treatment was necessary to the satisfactory performance of his invention. Referring generally to what was known in the prior art was held insufficient to satisfy the best mode requirement.

Even patents for simple inventions can be invalidated for failing to disclose the best mode. In a 2008 case, claims directed to a method for making wash-and-wear shirts were invalidated because the patentee failed to disclose the specific brand of glue used, despite the patentee’s argument that it had refrained from specifying the brand because the USPTO prefers the generic names of products to trade names.

Given the uncertainty over whether a description of the best mode will be found to be “adequate” and whether a detail is “routine,” patent drafters should err on the side of providing more detail. And let Ajinomoto give warning that a misleading mode should never be provided in lieu of the best mode.

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