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Enzo Biochem, Inc. v. Calgene, Inc., No. 98-1438, -1479, 188 F.3d 1362, 52 U.S.P.Q.2d (BNA) 1129 (Fed. Cir. Sept. 24, 1999).


Where undue experimentation was necessary to practice antisense technology in cells other than prokaryotes, the claims at issue failed for lack of enablement and were invalid.



Enzo Biochem, Inc. ("Enzo") is the licensee of three patents: U.S. Patents 5,190,931 ("the '931 patent"), 5,208,149 ("the '149 patent"), and 5,272,065 ("the '065 patent"), all three of which claim aspects of genetic antisense technology that was developed in E. coli. Antisense technology describes a process whereby the production of targeted proteins of an organism is inhibited. Enzo brought suit for infringement against Calgene, Inc. ("Calgene"), the producers of the FLAVR SAVR tomato. This invention employs antisense technology to block expression of specific proteins, thereby inhibiting ripening in tomatoes. Calgene, inter alia, counterclaimed seeking a declaratory judgment that the '065 patent was invalid as not enabled, as obvious, and as anticipated. The district court held that the FLAVR SAVR tomato did not infringe any of the claims at issue in the '931 and '149 patents and that those claims were invalid. Enzo appealed the finding of invalidity of the '931 and '149 patents. Calgene cross-appealed the district court's refusal to address the validity of the '065 patent and its denial of an award of attorney's fees because the claim was not deemed exceptional.

The Federal Circuit affirmed the lower court's invalidation of patents '931 and '149 on the grounds of lack of enablement. The Court stated that the '931 and '149 patents provided only a basic blueprint, "the mere germ of the idea," for exploiting the technology in eukaryotes. Using the Wands factors, the Court then determined that undue experimentation was necessary to practice antisense technology in cells other than prokaryotes; therefore, the claims at issue failed for lack of enablement and invalidity.

The Court also affirmed the finding that Calgene had failed to meet its burden to prove invalidity of the '065 patent. The Court emphasized that, as with claims within one patent, patents themselves are presumed independently valid. Calgene could not apply its arguments for the '931 and '149 to the '065 patent. Calgene did not present clear and convincing evidence that the '065 patent was not enabled. Therefore, dismissal of the counterclaim on the merits was proper. The Court noted that if Calgene had made even a modest attempt at an invalidity analysis, it might have prevailed.

The Court, however, remanded the request for attorney fees for a determination of whether there had been inequitable conduct during the patent prosecution. The lower court failed to decide whether Enzo employed inequitable conduct before the Patent and Trademark Office (PTO) in obtaining its patent. This determination must be made prior to assessing whether this case is exceptional under 35 U.S.C. § 285 for the purpose of awarding attorney fees.



1. Whether undue experimentation would have been required to make and use the '931 and '149 patents.

2. Whether the district court erred in dismissing Calgene's counterclaim on the '065 patent, which is substantially similar to the '931 and '149 patents.

3. Whether the district court erred in not deciding the issue of Enzo's inequitable conduct before the Patent and Trademark Office prior to ruling on whether this was an exceptional case under 35 U.S.C. § 285.


1. Yes. Using the Wands factors, the amount of experimentation required to practice the invention in cells other than prokaryotes required undue experimentation.

2. No. Each patent is independently presumed to be valid and must be independently shown to be invalid. Calgene failed to show any "real evidence" of invalidity, therefore, the '065 patent remained valid.

3. Yes. According to precedent, the district court failed to determine whether Enzo committed inequitable conduct before the PTO prior to determining whether this was an exceptional case under 35 U.S.C. § 285.


Cases Cited by the Court

Other Sources Cited by the Court


State of the Law Before Enzo

Whether the making and using of an invention would require undue experimentation, and thus whether a disclosure would meet the enabling requirement under 35 U.S.C. § 112, paragraph 1, is a legal conclusion based on underlying factual inquiries. See Johns Hopkins Univ. v. Cellpro, Inc., 152 F.3d 1342, 1354 (Fed. Cir. 1998). The Federal Circuit reviewed this question of law de novo. See id.

The enablement requirement of 35 U.S.C. § 112, paragraph 1 provides that "[t]he specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same…." 35 U.S.C. § 112, paragraph 1 (1994). For a patent specification to be enabling it must teach those skilled in the art how to make and use the full scope of the claimed invention without having to perform "undue experimentation." See Genentech, Inc. v. Novo Nordisk, 108 F.3d 1361 (Fed. Cir. 1997).

To determine what constitutes undue experimentation in a given case, courts should apply a standard of reasonableness, in light of the nature of the invention and the state of the art at the time the patent application was filed. See In re Wands, 858 F.2d 731, 737 (Fed. Cir. 1988); Hybritech, Inc. v. Monoclonal Antibodies, Inc., 802 F.2d 1367 (Fed. Cir. 1986). The Federal Circuit has enumerated a list of factors to consider when determining whether a specification requires undue experimentation: "(1) the quantity of experimentation necessary, (2) the amount of direction or guidance presented, (3) the presence or absence of working examples, (4) the nature of the invention, (5) the state of the prior art, (6) the relative skill of those in the art, (7) the predictability or unpredictability of the art, and (8) the breadth of the claims." See Wands, 858 F.2d at 737. These factors, however, are illustrative, not mandatory. See Amgen, Inc. v. Chugai Pharm. Co., 927 F.2d 1200, 1213 (Fed. Cir. 1991). The facts of each case determine which Wands factors are relevant. Id. The specification does not have to exemplify every aspect of the claim to enable the full scope of the claimed invention, but it must contain a reasonable amount of detail to enable those of ordinary skill in the art to make and use the invention as broadly as claimed. See In re Vaeck, 947 F.2d 488, 496 (Fed. Cir. 1991); Genentech, 108 F.3d at 1366.

Effect of Enzo on Current Law

The Federal Circuit concluded that the claims of Enzo's '931 and '149 patent are invalid as nonenabled because "undue experimentation" would be required to duplicate the results in other organisms. By determining that success and adequate disclosure of a genetic technique in one organism imputes merely a "germ of an idea" in relation to other organisms, the court has implied that patents for genetic techniques are limited to the specific organisms on which the patentee has enabled the invention. A patentee may not broadly claim a technique without a showing that all organisms can be similarly manipulated by reasonable experimentation. This is a high standard for the biologist to meet. Most experimentation is performed in the prokaryotic bacteria E. coli, yet most practical applications are limited to eukaryotic cells such as yeast, mammalian, and in this case, plant. The Court limited this principle by leaving for another day the issue of whether a claim accomplished in one type of prokaryote is limited solely to that particular prokaryote or may be considered enabled as to all prokaryotes.

In this case, the independently valid and enabled claim 74 of patent '931, which is directed only to prokaryotes, becomes invalid and unenforceable because it "failed" together with claim 1. The Court noted that it was "puzzl[ed] as to why a claim reading only on prokaryotes would be asserted against a tomato, which is clearly eukaryotic." Discussion, Section B, Para. 34. This seems to indicate that although the decision was directed at eukaryotes, patent claims for prokaryotes were additionally affected.

The Court held that although the '065 patent is substantially similar to the invalidated '931 and '149 patents, it must be independently shown to be invalid. The court states that "a party may not avoid its burden of proof by making a blanket statement that its proof with respect to one patent apply to another and not provide a formal analysis why that is true." Discussion, Section C Para. 6. Thus, similar patents must be independently asserted and argued before the court. Finally, the Court held that allegations of inequitable conduct before the PTO must be considered prior to ruling on the exceptional nature of the case with respect to attorney fees. The failure to consider inequitable conduct at the district court stage is erroneous and may result in remand.

Unanswered Questions

The Court did not independently consider whether the disclosure was sufficient to enable a claim encompassing the application of antisense technology to all prokaryotes. Does this mean that a claim of an invention enabled in one prokaryote is limited solely to that particular prokaryote or may be considered enabled as to all prokaryotes? The case also raises the question whether a claimant forfeits an otherwise valid claim by claiming it erroneously.

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