As is well known, when enforcing patents in China one of the difficulties faced by patentees is the challenge of evidence collection. By contrast, in patent infringement suits before U.S. courts, because there is a discovery procedure, both plaintiffs and defendants generally do not encounter difficulties in obtaining evidence. So what exactly are the rules governing discovery? Let’s take a look.
The discovery procedure is set out in the Federal Rules of Civil Procedure and is an important statutory pre-trial procedure in U.S. civil litigation. It allows both parties to obtain from each other, through a series of methods, evidence relevant to the case. This helps both sides understand the facts and promotes settlement or effective adjudication. Discovery is carried out by the parties themselves or led by their counsel, and the court intervenes only when necessary.
Why is discovery led by the parties rather than by the judge? When the plaintiff and defendant conduct discovery, each side will make every effort to search for and unearth evidence favorable to itself and to rebut all evidence favorable to the other side. At the same time, through this procedure each party gains a clearer understanding of the weaknesses in its own evidence, which is conducive to reaching a settlement.
In U.S. patent infringement litigation, discovery includes fact discovery and expert discovery. Expert discovery mainly involves opinions provided by experts retained by the parties on technical issues and on the calculation of economic damages. Below we focus on fact discovery, which may proceed through the following five methods:
Request for Production of Documents or Things: A party may request that the opposing party produce documents or tangible things relevant to the patent case, such as R&D drawings, prosecution histories, sales records for the accused products, accounting statements, etc.
Requests for Admissions: A party may ask the other side to admit facts not in dispute—for example, that the defendant received a cease-and-desist letter, or that the plaintiff’s patent was amended. Failure to respond within the prescribed period is deemed an admission.
Written Interrogatories: Through counsel, one party may pose a series of written questions related to the patent infringement dispute, requiring the other party to serve written answers within the time limit.
Depositions: This is a commonly used form of discovery in practice. Counsel for one party takes sworn testimony outside of court from the opposing party or its witnesses—typically in a law office or other suitable venue. A court reporter attends throughout and records verbatim all questions, answers, and objections, and there is audio/video recording as well. The resulting transcript and recordings may later be used as evidence at trial.
Subpoenas: Upon a party’s application, the court compels a person to appear to testify and/or to produce evidence.
These forms of discovery enable both sides to present the facts of the case through evidence, allowing the court to adjudicate the matter and render a fair judgment.
During expert discovery, expert witnesses primarily address issues such as calculating damages for patent infringement, providing objective and neutral bases for the court’s consideration.
It should be noted that when Chinese enterprises or individuals become involved in litigation in the United States, their production of documents, information, or tangible things pursuant to U.S. discovery may conflict with existing Chinese laws—such as the Personal Information Protection Law and the Law on Guarding State Secrets—especially where the cross-border provision of technical materials, personal information, data transfers, or potential state secrets is involved. In such circumstances, great caution is required. Parties should seek legal advice from qualified counsel in both China and the United States and adopt appropriate measures—such as data de-identification and applying for protective orders—to ensure compliance with the relevant laws of China.