A Markman hearing is a pretrial hearing in a U.S. District Court during which a judge examines evidence from all parties on the appropriate meanings of relevant key words used in a patent claim, when patent infringement is alleged by a plaintiff. It is also known as a "Claim Construction Hearing".[1]

Holding a Markman hearing in patent infringement cases has been common practice since the U.S. Supreme Court, in the case of Markman v. Westview Instruments, Inc., found that the language of a patent is a matter of law for a judge to decide, not a matter of fact for a jury to decide. In the United States, juries determine facts in many situations,[2] but judges determine matters of law.[3]

Markman hearings are important, since the court determines patent infringement cases by the interpretation of claims. A Markman hearing may encourage settlement, since the judge's claim construction finding can indicate a likely outcome for the patent infringement case as a whole. Markman hearings are before a judge, and generally take place before trial. A Markman hearing may occur before the close of discovery, along with a motion for preliminary injunction, or at the end of discovery, in relation to a motion for summary judgment. A Markman hearing may also be held after the trial begins, but before jury selection.

The evidence considered in a Markman hearing falls into two categories: intrinsic and extrinsic. Intrinsic evidence consists of the patent documentation and any prosecution history of the patent. Extrinsic evidence is testimony, expert opinion, or other unwritten sources; extrinsic evidence may not contradict intrinsic evidence.