In re ChromaCode Litigation

Background

California Institute of Technology and ChromaCode, Inc., together called ChromaCode, sued Bio-Rad Laboratories, Inc., alleging infringement of three patents. This motion concerned proposed amendments to ChromaCode’s infringement contentions for the ’170 and ’921 patents. Infringement contentions are the required written statements describing a patent owner’s theories of infringement and the products or processes accused of infringement.

The court applied Patent Local Rule 3-6, which allows amendment only with a timely showing of good cause. The court considered whether ChromaCode acted diligently in discovering the basis for each proposed amendment and in seeking the amendment, and whether Bio-Rad would suffer prejudice.

Single sample volume

ChromaCode proposed to eliminate its alternative theory that the relevant sample volume existed before the sample was partitioned into droplets. It retained its previously disclosed theory that the single sample volume could be a droplet. ChromaCode clarified that it was abandoning the alternative theory because it lacked evidentiary support, not asking for a narrower interpretation of the claim language.

The court allowed this amendment. It treated the change as eliminating one previously disclosed infringement theory rather than changing the underlying claim construction. Although the court found it unclear when ChromaCode determined that the alternative theory lacked evidentiary support, it concluded that removing a previously disclosed theory did not present the same concerns as failing to disclose a theory initially. The amendment was allowed because the court found no resulting prejudice to Bio-Rad.

Coding tables

ChromaCode sought to replace integer-based coding tables with decimal-based coding tables for the ’170 and ’921 patents. ChromaCode described the change as correcting tables that inadvertently suggested the accused assays used a degenerate coding scheme, even though its contentions alleged a non-degenerate scheme.

The court rejected that characterization. It found that the proposed tables reflected a material change in ChromaCode’s theory of how the accused assays satisfied patent limitations requiring a non-degenerate coding scheme. The court found that ChromaCode had not shown diligence in discovering the basis for this change. It therefore denied the request to use the proposed new coding tables and did not need to decide prejudice, although it stated that Bio-Rad would be prejudiced by the change.

Accused assays

ChromaCode sought to add three accused instrumentalities: Bio-Rad assay 3542 and two assays performed by non-party Verily Life Sciences. ChromaCode said it learned about these assays during discovery and would rely on the same infringement theories it used for the originally identified assays.

The court allowed the addition of the 3542 assay. Although ChromaCode did not explain its diligence in its opening motion, the court determined that the 3542 assay appeared to be part of, or essentially identical to, an assay or kit already included in the original contentions. The court also found that adding it would not prejudice Bio-Rad.

The court denied the request to add the Verily assays. ChromaCode acknowledged receiving detailed information about them in September 2024 and January 2025, but it did not seek leave to amend until July 2025. The court found that ChromaCode was not diligent in seeking the amendment after discovering the basis for it. Because of that finding, the court did not need to decide whether Bio-Rad would be prejudiced.

Bates-number citations and final disposition

Bio-Rad did not object to replacing citations using document web addresses with citations using Bates numbers. The court granted that portion of the motion as unopposed.

The court’s final dispositions were:

The court ordered ChromaCode to serve amended infringement contentions consistent with the order by October 23, 2025, unless the parties agreed to a different date.