Mondis Tech. Ltd. v. LG Electronics Inc., Appeal Nos. 2023-2117, -2116 (Fed. Cir. Aug. 8, 2025)

Our Case of the Week focuses on the written description requirement, and, in particular, how that requirement is considered following a jury verdict that the written description requirement is satisfied.

Mondis’s patent in suit concerns computer monitors.  It is titled “Display Unit with Communication Controller and Memory for Storing Identification Number for Identifying Display Unit.”  The patent describes a system for controlling a specific display unit, such as a computer monitor, that is configured to receive video signals from an external source, such as a computer.  The display unit’s memory stores one or more identification numbers.  A computer may request control of a newly connected display unit by transmitting the computer’s individualized identification number, which the display unit then compares to a stored list of known identification numbers.  If the computer’s identification number matches a registered identification number in the display unit’s memory, the computer can control aspects of the display unit, such as its brightness and contrast.  If there is no matching identification number, the computer cannot control the display unit.  The patent consistently describes a one-to-one relationship in which one identification number corresponds to one device.  For example, the patent provides that “the microcomputer 7 in the display device 6 waits for sending of the identification number assigned to the computer 1, that is, the so-called ID number from the computer 1.”   After this registration process, “the computer 1 is allowed to control the display device 6.”

As initially filed, the patent claim at issue recited, inter alia, “an identification number for identifying said display unit.”  After the claim was rejected over the prior art, the patentee amended the claim as follows: “an identification number for identifying at least a type of said display unit.”  The claim issued, and Mondis sued LG.

At trial, LG put on expert evidence that the claim was invalid for lack of written description.  Mondis put on no rebuttal case.  Mondis’s own expert did testify that the patent did not expressly disclose the “type of” limitation.  The jury found infringement and no invalidity, and the district court denied JMOL on the issue of written description, noting the presumption of validity and the jury’s verdict.

On appeal, the Federal Circuit reversed and found the claim invalid, holding that the patent failed to disclose the “at least a type of” claim limitation.  Mondis argued that LG’s expert simply failed to convince the jury and that the jury had the right to disregard his testimony because he was impeached.  The Federal Circuit noted that, even if LG’s expert’s testimony was disregarded, the only other evidence was the patent itself and Mondis’s own expert’s admission that the patent did not disclose the “type of” limitation.  The Court held that the jury did not have substantial evidence in support of its no invalidity verdict.

Mondis also argued that the mere fact that the examiner issued the claim provided a heightened presumption that the examiner found written description support.  The Federal Circuit rejected that reasoning, and noted that the examiner gave no indication that he considered the written description question after the application claim was amended.

In reversing the district court and finding the claim invalid, the Federal Circuit also wiped out a $14 million verdict in favor of Mondis.

The opinion can be found here.

By Nika Aldrich

This article summarizes aspects of the law and does not constitute legal advice. For legal advice with regard to your situation, you should contact an attorney.