Inherency.

• Author: Burk, Dan L.
• Position: Patent law

TABLE OF CONTENTS

INTRODUCTION I. ANTICIPATORY INHERENCY A. False Starts B. Public Benefit C. Knowledge and Use II. POSSESSORY INHERENCY A. Disclosure Cases B. Priority Cases III. EXTENDING INHERENCY ANALYSIS A. Inherent Obviousness B. Inherent Infringement C. Inherent Products of Nature D. Foreign Inherency CONCLUSION INTRODUCTION

Inherency is a puzzle that runs throughout patent law. Patents are based upon descriptions of technology. The description of the invention in a patent distinguishes it from previous technologies described in the prior art. The description of the claimed invention in a patent determines whether an accused device infringes the patent. The description of the invention in a patent application is used to determine whether the claimed invention is sufficiently novel, useful, and nonobvious to merit a patent at all. Indeed, the fundamental premise of patent law is that of a bargain between the inventor and the public: the public authorizes twenty years of exclusive rights in exchange for the publication of a detailed description of how to make and use the claimed invention.

Technologies may have qualities that are unappreciated or unidentified in a patent description, but which are nonetheless present. The law refers to these unknown attributes as "inherent" in the product or process. What should be done about such characteristics or qualities of a technology that exist but are not explicitly described, either through ignorance or inadvertence? This problem is explicitly presented in at least five different patent doctrines: anticipation, (1) the on-sale bar, (2) priority disputes, (3) double-patenting, (4) and enablement (5); and it casts its shadow across the law governing subject matter, infringement, and obviousness. The Federal Circuit has decided dozens of cases involving inherency in the last twenty years. Depending on how it has been applied, (6) the inherency doctrine permits defendants to invalidate a patent by showing that even though the prior art did not expressly disclose what the patentee claims to have invented, all or part of the patentee's invention was inherent in a particular piece of prior art. It may also permit patent owners to satisfy their obligation to provide an enabling disclosure, and perhaps even to prove a date of invention, based on information that they do not disclose but that is inherent in their invention.

Inherency is also perhaps the most elusive doctrine in all of patent law. It has confused and annoyed generations of law students. However, the confusion hardly ends there. Commentators have struggled to explain the doctrine and have come up with formulations strongly reminiscent of epicycles that are at least as confusing as the case law. (7) The courts, too, are confused. The cases appear to flatly contradict each other, are often accompanied by dissents, and in the last three years alone have triggered one abortive en banc rehearing (8) and strong calls for a second. (9) In particular, the courts have split sharply over whether an element can be inherent in a prior art reference even if people of ordinary skill in the art do not appreciate the existence of that element. (10)

In this Article, we argue that this confusion is largely unnecessary. Examining the facts of the cases offers a simple way to understand them. While many courts have recited as gospel the idea that inherency requires knowledge or appreciation of the inherent element, in no case does the application of the inherency doctrine actually turn on knowledge of the element. Indeed, on reflection, application of a knowledge standard in inherency cases makes little sense. Inherency by definition concerns things that people of ordinary skill in the art do not know; if the person having ordinary skill in the art (PHOSITA) would know of the presence of an element based on the prior art disclosure, there is a straightforward case of anticipation based on that disclosure and no need for the inherency doctrine. (11) Rather, the inherency cases are all ultimately about whether the public already gets the benefit of the claimed element or invention. If the public already benefits from the invention, even if they don't know why, the invention is inherent in the prior art. If the public doesn't benefit from the invention, there is no inherency.

In Part I, we examine the main thread of inherency cases, those arising out of the novelty and statutory bar provisions of the Patent Act. We explain how the courts got off track in their focus on knowledge and why a focus on benefit clearly and consistently explains the doctrine. In Part II, we consider inherency in a different context, one in which the inventor must show possession of the claimed invention, either to prevent a "new matter" rejection or to establish priority of invention. Finally, in Part III, we discuss the broader implications of this rule, including what the inherency doctrine may mean for patents on DNA sequences and patents on drugs derived from traditional knowledge. A proper understanding of the inherency doctrine may offer a logical explanation for the "product of nature" cases, undermining the last significant exception to patentable subject matter.

1. ANTICIPATORY INHERENCY

   Although the inherency problem manifests itself across a range of patent doctrines, it is perhaps best known, and most often seen, in the context of 35 U.S.C. [section] 102, the statutory section dealing with novelty and "loss of right," the statutory bar to patentability. (12) Section 102 defines the novelty requirement in terms of public knowledge or use, or description in print prior to the date of invention. (13) It defines the statutory bar in terms of description in print or public use or sale more than one year prior to the filing of a patent application. (14) These criteria have led to a long line of cases struggling to determine precisely what aspects of an invention need to be known or described, what needs to be used or sold prior to the critical date in order to defeat patentability, and, most especially, what the consequence might be if the invention is inherent in the prior art. The knowledge and written description bars don't generally raise inherency concerns; an invention is either known or described or not. But these questions proved much thornier in the case of unwitting or inadvertent sales or uses.

   1. False Starts

      The story of inherency begins with the 1880 Supreme Court case of Tilghman v. Proctor. (15) The inventor in that case claimed a process for breaking down animal fat into glycerine and free fatty acids, both of which could be used to make products ranging from candles to soap. (16) The process required mixing fat with water and subjecting the mixture to high temperature and pressure. (17) As it turns out, the same process of separating glycerine from fatty acids had undoubtedly occurred fortuitously when a prior art steam engine was lubricated with animal fat, since a steam engine has water, pressure, and high temperature. (18) The Court concluded that the accidental anticipation of the patented process should not bar Tilghman from getting a patent on the process. (19) The Court emphasized that the separation of the tallow in the operation of the prior art steam engine was neither recognized by those of skill in the art nor used for the purpose for which it was later patented. (20) Rather, it was considered an unintended waste product, not an intended result of the use of the prior art machine. The Court wrote that

      [t]hose engaged in the art of making candles, or in any other art in which fat acids are desirable, certainly never derived the least hint from this accidental phenomenon in regard to any practicable process for manufacturing such acids.... If the acids were accidentally and unwittingly produced, whilst the operators were in pursuit of other and different results, without exciting attention and without its even being known what was done or how it had been done, it would be absurd to say that this was an anticipation of Tilghman's discovery. (21) This language has become the standard formulation of the doctrine of inherency. In Eibel Process Co. v. Minnesota & Ontario Paper Co., (22) for example, where the Court found that there was no inherent production of the invention at all, the Court also noted in the alternative that "accidental results, not intended and not appreciated, do not constitute anticipation." (23)

      The results in Tilghman and Eibel were overdetermined. (24) In Tilghman, the invention was neither understood nor used in the prior art. Similarly, in Eibel, the Court was not persuaded that the invention was produced at all in the prior art, so it was free to state the test for inherency without having actually to apply that test to the case before it. As a result, in both cases the Court could be imprecise in its formulation of the inherency test. And it was. The Court in Tilghman offered two different reasons why the invention was not inherently anticipated: those of skill in the art did not understand that it was present in that art and the public was not using or benefiting from the prior use of the process. (25) Were both elements required for inherency to attach? Would either one suffice to prove inherency? Or was one of the factors dominant and the other simply playing a supporting role? Because neither element was present, the Court did not resolve these questions.

      The result was a general statement of the inherency test that is unworkable in practice and which has been responsible for much of the doctrinal confusion that has resulted. The Federal Circuit has repeatedly cited Tilghman for the proposition that inherent anticipation requires the PHOSITA to recognize and understand the presence of the anticipation in the prior art. In Continental Can Co. USA v. Monsanto Co., for example, the court recited the requirement that the missing element must be both necessarily present and "that it...