Ningde Amperex Technology Limited v. Zhuhai CosMX Battery Co., Ltd.

Summary

The United States District Court for the Eastern District of Texas grants in part and denies in part Ningde Amperex Technology Limited’s second motion to supplement its infringement contentions. The court denies leave to add a doctrine-of-equivalents theory and additional accused products for lack of diligence and good cause, but grants the unopposed request to correct compaction-density calculations for previously disclosed cells.

Holdings

1. Plaintiff failed to show the diligence required for good cause because it had access to the information supporting the doctrine-of-equivalents theory since February 11, 2025, yet sought supplementation only after filing an earlier motion and long after receiving the information. The request was denied.
2. Plaintiff failed to establish good cause to add the proposed additional products because the request was made late, concerned a large volume of products, and would substantially prejudice Defendant by leaving insufficient time for responsive testing and analysis. The request was denied.
3. Plaintiff was permitted to correct the compaction-density calculations concerning infringement of the '118 Patent for cells previously disclosed in its first amended infringement contentions because Defendant did not oppose that request.

Questions Presented

1. Whether Plaintiff established good cause under Patent Local Rule 3-6(b) to add a doctrine-of-equivalents theory to its infringement contentions.
2. Whether Plaintiff established good cause under Patent Local Rule 3-6(b) to add additional allegedly infringing products for the '118 and '148 Patents.
3. Whether Plaintiff should be permitted to correct compaction-density calculations for cells previously disclosed in its first amended infringement contentions when Defendant did not oppose that request.

Disposition

other