Largan Precision Co, LTD v. Motorola Mobility, LLC.

Background

Largan sued Motorola for allegedly infringing claims from U.S. Patent Nos. 8,310,767 and 9,784,948 concerning optical lens assemblies. Motorola contests the validity of the patents. The order concerned a joint discovery letter in which Motorola sought to prevent Largan from relying on three categories of late-disclosed information.

Largan’s original and amended infringement contentions used priority-date language stating dates "no later than" specified dates. On January 21, 2025, Largan supplemented an interrogatory response with earlier reduction-to-practice dates for the two patents. The court treated that response as an attempt to amend Largan’s infringement contentions. Largan had served its original contentions in March 2022, and fact discovery closed on February 20, 2025.

Largan also produced conception documents for the ’767 Patent after its corporate witness testified that he had relied on documents that had not previously been produced. On the last day of fact discovery, Largan made certain SEQ design files available for inspection. Largan described those files as source-code files for optical-design software concerning model numbers identified as practicing the asserted patents.

Legal standard

The Patent Local Rules require a patent claimant to disclose its infringement theories and supporting information early in the case. The rules require disclosure of asserted claims and priority dates, as well as documents concerning conception, reduction to practice, design, and development. They also require documents sufficient to show the operation of accused instrumentalities that the claimant relies on as embodying asserted claims.

A party may amend infringement or invalidity contentions only by court order after a timely showing of good cause. The moving party must show diligence both in discovering the basis for the amendment and in seeking amendment after discovering it. The court may also consider prejudice to the opposing party.

Rulings

The court granted Motorola’s motion.

Earlier priority dates. The court held that Largan’s supplemental interrogatory response was an attempt to amend its infringement contentions. Largan served the response nearly three years after its original contentions and did not explain why it could not have found the earlier dates sooner. The court found that Largan failed to establish diligence. It also stated that Motorola would be prejudiced by the new dates, which were asserted about one month before fact discovery closed. The court therefore struck the portions of Largan’s supplemental response identifying priority dates earlier than those in Largan’s prior infringement contentions.

Conception documents. The court precluded Largan from relying on the late-produced conception documents for the ’767 Patent. It found that Largan did not explain why it had been unaware of the documents earlier, failed to establish diligence, and did not show good cause for failing to produce them with its infringement contentions as required by Patent Local Rule 3-2(b).

SEQ design files. The court also precluded Largan from relying on the SEQ design files made available on the last day of fact discovery. Largan did not establish diligence or explain why it had not produced the materials earlier. The court rejected Largan’s attempt to attribute any resulting prejudice to Motorola.

Disposition and scope

The order granted Motorola’s discovery motion and imposed the three stated restrictions on Largan’s evidence and contentions. It did not decide the patent-infringement claims, the validity of the patents, or any other ultimate merits question.