Inter partes reviews (IPR) are limited by statute to grounds of invalidity under 35 U.S.C. §§ 102 (novelty requirement) and 103 (nonobviousness requirement) and on the basis of prior art patents or printed publications.

Other grounds for challenging patent validity, such as insufficient written description or lack of enablement, are unavailable. Also unavailable are challenges under 35 U.S.C. § 101, which excludes abstract ideas, laws of nature and natural phenomena from subject matter eligibility.

Or so we thought, until we read the recent decision in Praxair Distribution, Inc. v. Mallinckrodt Hospital Products IP Ltd. A crack can now be discerned in the prohibition on asserting section 101 issues in IPR proceedings.

Under the “printed matter doctrine,” which has its roots in 35 U.S.C. § 101, claim limitations directed to the content of information were not entitled to patentable weight unless there was a functional relationship to the substrate on which the printed matter was applied. While the printed matter doctrine was originally limited to matter physically printed on substrates like labels and information leaflets, its current reach extends to information stored on electronic media such as databases.

A claim element denied patentable weight is effectively plucked out of the claim when its subject matter is compared to the prior art, so the excluded element can no longer be relied upon to uphold claim patentability under 35 U.S.C. §§ 102 and 103.

In Praxair, the Federal Circuit brought not only the “printed matter doctrine” into play, but further extended the doctrine’s reach to include certain mental steps. As a result, even though 101-based challenges are formally prohibited by the IPR statute, they have now found an expanded role in IPR proceedings.

Patentability of Informing Steps

U.S. Patent 8,846,112 claims methods of distributing nitric oxide gas cylinders for treating neonates with hypoxic respiratory failure. Praxair researchers discovered a side effect of nitric oxide treatment, namely, that in neonates with left ventricular dysfunction, inhaled nitric oxide may lead to pulmonary edema.

In an effort to obtain patent protection for this finding, a number of claims are aimed at distributors that supply medical providers with nitric oxide in combination with a warning against treating a patient with left ventricular dysfunction.

For example, claim 1 includes the steps of:

• “supplying […] nitric oxide gas to a medical provider […]” and
• “providing to the medical provider
• (i) information that a recommended dose of inhaled nitric oxide gas for treatment of neonates with hypoxic respiratory failure is 20 ppm nitric oxide and
• (ii) information that, in patients with preexisting left ventricular dysfunction, inhaled nitric oxide may increase pulmonary capillary wedge pressure (PCWP), leading to pulmonary edema,
• the information of (ii) being sufficient to cause a medical provider considering inhaled nitric oxide treatment for a plurality of neonatal patients […] to elect to avoid treating one or more of the plurality of patients”

In construing the claims, the PTAB applied the printed matter doctrine, finding that claim limitations directed to the content of information supplied to the medical provider are not entitled to patentable weight.

The CAFC affirmed, citing to precedent establishing that (1) a claimed step of informing someone about an inherent property of a method is printed matter, and (2) merely adding an instruction sheet or other informational content to a drug product is not sufficient to create a functional relationship.

Mental Steps Are Also Not Entitled to Patentable Weight

Importantly, the PTAB expanded the reach of the printed matter doctrine to steps where the printed subject matter is mentally processed. Claim 3 of the patent, for instance, included evaluating steps performed in a medical provider’s mind on the basis of the information supplied in combination with the results of a diagnostic test:

• “performing at least one diagnostic process […]
• evaluating the potential benefit of treating [a] patient in order to arrive at a decision of whether or not to treat the […] patient […]”

Claim limitations reciting mental steps are not entitled to patentable weight, said the PTAB. The Federal Circuit agreed, stating that the evaluating limitation in claim 3 is directed to a mental step that

• is also printed matter […] This limitation merely requires a medical provider to think about the information claimed in the providing information limitation of claim 1. But adding an ineligible mental process to ineligible information still leaves the claim limitation directed to printed matter. To hold otherwise would make the printed matter doctrine a dead letter, requiring no more than a “think about it” step to give patentable weight to a claim limitation directed to information content.

Struggling to preserve the patentable weight of the mental steps, the patent owner objected that whether claims are directed to mental steps may only be considered in determining patent eligibility, not obviousness. The Federal Circuit disagreed, effectively opening the door to eligibility-based challenges in IPR proceedings, at least where mental steps can be defined as the processing of patent-ineligible information.

Though eligibility challenges are not part of IPR proceedings, the customary novelty and obviousness analyses may now be influenced by denying patentable weight to certain types of mental steps based on their subject matter ineligibility.