Chapter §7.11 Prior Invention Under §102(g)

• Jurisdiction: United States

§7.11 Prior Invention Under §102(g)

[A] Introduction

Section 102(g) of 35 U.S.C. (2006) is the cornerstone of the historic U.S. first-to-invent patent system. When two or more entities independently invent the same invention, only one will be granted a patent. U.S. patent law provides that the patent will be awarded to the entity that was the first in time to invent, rather than the first in time to file a patent application with the government (which is the rule in the rest of the world).⁸³¹

The requirement that a patent is to be awarded to the first to invent is implemented in two different contexts as indicated by the two-part structure of the text of 35 U.S.C. §102(g) (2006).⁸³² Section 102(g) comprises two prongs. The first prong, §102(g)(1), deals with priority contests called interferences between two or more parties who claim to have independently made the same invention at about the same time. The interference, an inter partes proceeding conducted within the USPTO, will determine which party was first to invent and hence entitled to the U.S. patent on the invention in question.⁸³³ Inventive activity that took place abroad is admissible evidence in an interference to the extent allowed by 35 U.S.C. §104 (2006).⁸³⁴

The second prong, §102(g)(2), deals with anticipation of the claims of a patent application (in ex parte prosecution) or an issued patent (in federal court litigation challenging validity). Anticipation is triggered by the act of someone other than the named inventor of the application or patent having made the invention in this country before the invention date of the application or patent. In contrast with interferences under §102(g)(1), anticipation under §102(g)(2) is a patent-defeating event that must have occurred in the United States.

In both the interference and the anticipation settings, the first-to-invent principle applies. Importantly, the earlier invention must not have been "abandoned, suppressed, or concealed."⁸³⁵ The interference and anticipation contexts are discussed separately below, following an analysis of the basic rule of time-wise priority that applies in both contexts.

[B] The First-to-Invent Priority Rule

[1] Statement of the Priority Rule

In both the interference and anticipation settings, the rather cryptic last sentence of §102(g) applies:

In determining priority of invention under this subsection, there shall be considered not only the respective dates of conception and reduction to practice of the invention, but also the reasonable diligence of one who was first to conceive and last to reduce to practice, from a time prior to conception by the other. ⁸³⁶

The quoted statutory provision can be restated in simplified form as the following rule for determining time-wise priority of invention:

Generally, the first to reduce to practice [who thereafter does not abandon, suppress, or conceal] is the first to invent, unless the last to reduce to practice is also the first to conceive and sufficiently diligent.

Application of this rule, whether in ex parte prosecution, validity litigation, or an interference proceeding, requires understanding several constituent concepts; that is, reduction to practice, abandonment/suppression/concealment, conception, and diligence. Each concept is discussed separately below.

[2] Reduction to Practice

U.S. patent law conceptualizes the act of inventing as a two-part process. Inventing begins with the mental conception of the invention (described below) and ends with its reduction to practice.⁸³⁷ A reduction to practice may occur in one of two forms: an actual reduction to practice or a constructive reduction to practice.⁸³⁸

[a] Actual Reduction to Practice

An actual reduction to practice occurs when a physical embodiment of the invention has been constructed or carried out that works for its intended purpose.⁸³⁹ In other words, the inventor must prove "that he [1] constructed an embodiment or performed a process that met all the limitations of the claim, and [2] that he determined that the invention would work for its intended purpose."⁸⁴⁰ For example, inventors of mechanical devices often build a physical prototype of their inventions and test the prototype. If the testing confirms that the invention works for its intended purpose, then the invention has been actually reduced to practice.

Some very simple inventions may not require testing to confirm their operability, although this is probably the exception rather than the rule. Nevertheless, "[i]n instances where the invention is sufficiently simple, mere construction or synthesis of the subject matter may be sufficient to show that it will operate satisfactorily."⁸⁴¹

For example, the invention in In re Asahi/America, Inc.⁸⁴² was a double (concentric) pipe system in which an inner "carrier" pipe carried a fluid while an outer "containment" pipe surrounded the inner pipe and contained any leaks. Such double containment pipe systems are used in the chemical industry to prevent leaks of corrosive materials. The claimed invention comprised the double containment pipe system (capable of using stock "off the shelf" pipes) as well as a "restraint coupling" to control the differential thermal expansion of the carrier and containment pipes. The Federal Circuit concluded that "the restraint coupling is so simple a device that mere construction of it is all that is necessary to constitute reduction to practice."⁸⁴³ Although the claims required a certain length relationship between the carrier and containment portions of the coupling, which was important in facilitating welding of the coupling to pipe sections, the Federal Circuit held that the length relationship was clearly shown in a photograph of the coupling that had been published in a trade journal prior to the date needed to establish priority of invention.

In the more typical case in which testing is required to confirm that the invention works for its intended purpose, the invention need not work perfectly nor even be in a commercially satisfactory stage of development. For example, in Taskett v. Dentlinger,⁸⁴⁴ an interference count covered a process for the automated purchasing of prepaid telephone services. One limitation of the count required "obtaining financial authorization" to purchase a certain amount of telephone services. The interference parties disputed whether Dentlinger had priority of invention through an actual reduction to practice. In testing the process, Dentlinger used a dummy checking account and a switch at his own employer, rather than seeking financial authorization from a third-party financial institution holding actual money in an actual account. The Federal Circuit held that Dentlinger's testing was sufficient for an actual reduction to practice, despite the fact that he did not carry out the "financial authorization" step of the process under conditions of actual use. The testing was sufficient to determine that the process would work for its intended purpose. The court explained that "[t]o hold otherwise would be to require an inventor to have created a viable commercial embodiment before the [USPTO] Board or a court could find reduction to practice. This the law does not require."⁸⁴⁵

Testing of the physical embodiment of an invention for purposes of an actual reduction to practice may be carried out under conditions that differ from those of the invention's intended environment, if the testing conditions sufficiently simulate the actual use conditions. DSL Dynamic Sci. Ltd. v. Union Switch & Signal, Inc.⁸⁴⁶ illustrates this principle. The interference parties in DSL disputed priority of invention of a "coupler mount assembly" used to clamp various equipment, such as a brake pressure monitor, to the coupler between railway cars. Union Switch sought to establish an actual reduction to practice based on its testing of a prototype coupler mount assembly on cabooses of trains. DSL contended that cabooses were not the intended environment for the invention. Instead, the claimed coupler mount assembly would in reality be attached to a coupler between freight cars, which have less cushioning and a more minimal suspension system than passenger-carrying cabooses.

The Federal Circuit disagreed with DSL. Although an actual reduction to practice requires a showing that the embodiment relied on as evidence of priority actually worked for its intended purpose, even if the "intended purpose" is not explicitly set forth in the interference count,⁸⁴⁷ "tests performed outside the intended environment can be sufficient to show reduction to practice if the testing conditions are sufficiently similar to those of the intended environment."⁸⁴⁸ In the case at bar, Union Switch's tests were extensive. Trains with the coupler prototype mounted thereon traveled over 700 miles. The coupler mount assembly operated successfully even when forces "in excess of 15 G's" were applied to it. These conditions sufficiently approximated the "loads to 20G" that DSL's expert witness indicated a coupler mount assembly would have to withstand on a non-cushioned rail car such as a freight car. The DSL expert's conclusion that Union Switch's tests were not adequate wrongly related to how well the coupler assembly prototype worked, not whether it worked at all. The Federal Circuit concluded that Union Switch's tests "sufficiently establish[ed] that the device would work to hold equipment on a moving rail car, even if that rail car was not a caboose."⁸⁴⁹ This was sufficient to establish an actual reduction to practice.

Even when an inventor has established that he constructed an embodiment or performed a process that met all limitations of the claim (or "count," in interference parlance) and that the embodiment worked for its intended purpose, the Federal Circuit requires that an additional requirement be met: corroboration of the actual reduction to practice. It is not enough that the inventor himself testifies to the facts of the reduction to...