Unquestionably, the narrower a patent’s claims, the more likely they are to pass muster under 35 U.S.C. § 101. But if you have an invention with broad applicability, how broadly can you claim it without running into eligibility problems? The answer, both literally and figuratively: the sky’s the limit.

In Thales Visionix Inc. v. United States, Appeal No. 2015-5150 (Fed. Cir. Mar. 8, 2017), the Federal Circuit, in an opinion authored by Circuit Judge Moore joined by Circuit Judges Wallach and Stoll, held patent-eligible a claim to a one-step method to “determining” the orientation of an object relative to a moving reference frame:

22. A method comprising determining an orientation of an object relative to a moving reference frame based on signals from two inertial sensors mounted respectively on the object and on the moving reference frame.

Slip op. at 4. The court held eligible also a “system” claim almost as broad as the method claim:

  1. A system for tracking the motion of an object relative to a moving reference frame, comprising:

a first inertial sensor mounted on the tracked object;

a second inertial sensor mounted on the moving reference frame; and

an element adapted to receive signals from said first and second inertial sensors and configured to determine an orientation of the object relative to the moving reference frame based on the signals received from the first and second inertial sensors.


The United States Court of Federal Claims granted a motion for judgment on the pleadings holding the plaintiff’s patent invalid for claiming a “patent-ineligible law of nature.” 122 Fed. Cl. 245, 248 (2015). Some explanation of the invention, not fully described in the Federal Circuit’s opinion, will help to understand the Federal Circuit’s reversal of the Claims Court.

The F-35 Joint Strike Fighter is the first fighter jet that, instead of displaying information in a fixed position on a surface inside the cockpit, employs a helmet-mounted display system on the interior of the pilot’s helmet’s visor, which allows the pilot to target enemies in all directions. The patent describes how to continuously track the orientation of the helmet relative to the moving aircraft to provide the display with current and accurate information, explaining that any interval of time between helmet rotation and the presentation of visual data can cause both a discrepancy between information expected and presented and also pilot disorientation and nausea. Id. The prior art used inertial sensors, such as accelerometers and gyroscopes, to track the motion of an object relative to the earth, but small errors in the measurement of acceleration and angular velocity translate into large errors over time and require intermittent correction. Slip op. at 2-3. The patent discloses that tracking the motion of both an aircraft and the helmet relative to the earth produces inconsistent position information when the aircraft accelerates or turns. Id. at 3.

To increase the efficiency and accuracy of tracking the location and orientation of the helmet, the inventors derived equations for tracking the movement of an object relative to a moving platform instead of tracking both object and platform relative to the rotating earth and then attempting to fuse the information. Thus, the invention requires inertial sensors on both the tracked object and the moving reference frame that gather orientation data that is applied to the derived navigation equation. The resulting system and method obviously could be used to track any object relative to a moving reference frame, and the inventors therefore chose to claim the invention broadly to read on any tracked object and moving reference frame employing any type of inertial sensors. 122 Fed. Cl. at 250.

The Federal Circuit emphasized that the patent discloses an unconventional approach: Instead of measuring the motion of an object and platform relative to the earth, the moving platform inertial sensors directly measure the gravitational field in the platform and the object inertial sensors calculate the position of the object relative to the moving platform. Slip op. at 3. That has several advantages: increasing accuracy, operating without additional hardware to determine the position of the moving platform, and easier installation of the system because it is installed entirely on the inside of the moving platform. Id. at 3-4.

The Federal Circuit disagreed with the Claims Court’s holding that the claims are directed to the abstract idea of using laws of nature governing motion to track two objects, i.e. step one of the Supreme Court’s test under Alice Corp. Pty. v. CLS Bank Int’l, 134 S. Ct. 2347 (2014), and therefore did not address step two. In addition to its own cases, the Federal Circuit relied most heavily on Diamond v. Diehr, 450 U.S. 175 (1981). The claimed method for molding uncured rubber into cured rubber products in that case employed the Arrhenius equation to calculate the optimum duration of molding using the internal temperature of the mold. The Federal Circuit noted that the Supreme Court held the claims patent-eligible because the process began with loading the mold and ended with opening the press to produce a perfectly cured product. The Federal Circuit quoted the Supreme Court’s explanation that “when a claim containing a mathematical formula implements or applies that formula in a structure or process which, when considered as a whole, is performing a function which the patent laws were designed to protect,” the claim is patent-eligible. Slip op. at 8 (quoting Diehr, 450 U.S. at 192). The Diehr claims, the Federal Circuit concluded, were “directed to” an improved rubber curing process, not a mathematical formula. Id.

Despite the specificity of the Diehr claims, the Federal Circuit reasoned that the claims on appeal “are nearly indistinguishable from the claims at issue in Diehr.” Id. The court relied on the requirements in the claims for first and second inertial sensors on the tracked object and the moving platform and the determination of the orientation of the tracked object based on data supplied by the inertial sensors. “Just as the claims in Diehr reduce the likelihood that the rubber molding process would result in ‘over curing’ or ‘under curing,’ . . . the claims here result in a system that reduces errors in the inertial system that tracks an object on a moving platform.” Id. at 9 (citation omitted). The court attributed that improvement to the “unconventional combination of sensor placement and calculation based on a different reference frame.” Id. at 10. The court concluded, “Far from claiming the equations themselves, the claims seek to protect only the application of physics to the unconventional configuration of sensors as disclosed. As such, these claims are not directed to an abstract idea.” Id. at 11 (emphases added).

An earlier article, entitled Federal Circuit Provides Additional Guidance in Reversing Holding of Patent-Ineligibility of Biotech Invention, concluded, inter alia, “A claim that applies a law of nature or abstract mental process merely by reciting a step of observing, identifying, detecting, or comparing may be held to be ‘directed to’ the law of nature or abstract mental process.” Reading the claims on appeal in Thales Visionix, especially the one-step method of “determining,” one might have agreed with the Claims Court that the claims were “directed to” an abstract idea. Indeed, the Claims Court deemed it “clear that the [system] claim is ‘directed to’ the determining step accomplished by the element’s configuration to perform the navigation equations,” and that the method claim “is nothing more than an instruction to solve a navigation equation.” 122 Fed. Cl. at 251-52.[1] The key to the Federal Circuit’s holding appears to be a system and method that could be described as “unconventional” and result in a significant improvement.[2] The obvious lesson for patent owners attempting to rebut a challenge to patent eligibility is to describe the claimed invention as an unconventional approach that produces significantly improved results.