Inherency and obviousness have long been separate invalidity inquiries. The Federal Circuit recently intimated in Allergan, Inc. v. Sandoz Inc., however, that this separation could soon be a thing of the past. In particular, the majority and dissenting opinions suggest that, at least in certain circumstances, “the inherency doctrine may apply to an otherwise obvious claim.” If inherency and obviousness become merged, particularly in the way that the Allergan dissent urged, there are several consequences that litigants should be mindful of when navigating anticipation and obviousness.

In Allergan, the asserted patent included both composition and method-of-treatment claims directed to a combination ophthalmic drug treatment (0.2 percent brimonidine and 0.5 percent timolol). The majority found the composition claims obvious because: both compounds were commercially available in their claimed concentrations, the compounds were known to be more effective when administered serially than when administered alone, and the prior art provided motivation to combine the compounds to increase patient compliance. The majority concluded that the patent holder’s evidence of unexpected results (increased efficacy and reduced side effects) and teaching away were insufficient to overcome Sandoz’s “strong case” of obviousness.

On the other hand, the Federal Circuit held that a method of reducing the number of ophthalmic treatments from three to two times per day without a loss of efficacy was not obvious, finding that the prior art failed to disclose that the combination, when administered twice a day, “would eliminate the afternoon trough issue.” In dissent, Judge Dyk argued, citing anticipation case law, that the method claim was obvious under the law of inherency because “‘loss of efficacy’ is not a separate step, but rather a result of the claimed method,” and “a newly-discovered result or property of an existing (or obvious) method of use is not patentable.’” Importantly, in justifying its finding of nonobviousness in view of the dissent, the majority suggested that it may have applied an inherency analysis if the record evidence had been more complete. (“We agree with the dissent that the inherency doctrine may apply to an otherwise obvious claim as well. There is, however, a problem with applying that doctrine in this case.”)

Before Allergan, the Federal Circuit had maintained a clear separation between inherency and obviousness. Judge Dyk’s dissent contravenes well-established Federal Circuit precedent — not mentioned in either the majority or the dissenting opinion — that “the inherency of an advantage and its obviousness are entirely different questions. That which may be inherent is not necessarily known. Obviousness cannot be predicated on what is unknown.” Indeed, the dissent’s approach could lead to the harsh consequence that inherent results would be obvious regardless of the disclosures of the prior art, and regardless of whether any “inherent” advantages of a novel process were known or suspected. Although the Allergan majority ultimately concluded, consistent with precedent, that the inherent results of an otherwise obvious process do not result in invalidity where the result is not actually disclosed in the prior art, the majority’s suggestion that inherency may have a place in an obviousness analysis could be foretelling a significant shift in the law.

If such a shift were to occur, there would be several consequences to patent holders and patent challengers. First, merging these doctrines would lead to courts focusing on whether method steps are obvious, and then determining whether the result of those steps is inherent. Second, unexpected properties could be eviscerated because courts would not need to consider whether the inherent properties of the claimed method were known or obvious before invalidating the claim. As the Federal Circuit continues to analyze these issues, litigants should proceed with caution. Patent holders should be aware that arguing unexpected properties may not necessarily win the day against an obviousness challenge, and could actually fuel an inherency-based defense that may be difficult to rebut. Patent challengers should craft their theories carefully, and consider the best course for their invalidity defenses in the face of a potentially shifting landscape for both anticipation and obviousness.