A Markman hearing is the pretrial proceeding in a U.S. patent case in which the judge determines what the disputed terms of the asserted patent claims mean. The name comes from the Supreme Court's 1996 decision in Markman v. Westview Instruments, Inc., 517 U.S. 370. The patent claims define the boundaries of the legal right, and an infringement analysis compares the construed claim against the accused product or process. Before a jury can decide whether those boundaries were crossed, someone has to fix what the boundaries are. Markman answered the question of who: the court.

The dispute in Markman centered on the word "inventory" in a patent for a system that tracked clothing through a dry-cleaning operation. The patentee argued the term covered tracking articles of clothing; the accused infringer argued it required tracking dollars and the cash inventory of a business. Whether the accused system infringed turned entirely on which reading was correct. A unanimous Supreme Court held that resolving that kind of interpretive question is a job for the judge, not the jury, and that the Seventh Amendment did not guarantee a jury trial on the meaning of claim terms.

"the construction of a patent, including terms of art within its claim, is exclusively within the province of the court."— Markman v. Westview Instruments, 517 U.S. 370 (1996), source

What the judge actually decides

At a Markman hearing the parties identify the claim terms they dispute and propose competing constructions for each. The court weighs the intrinsic record first — the claim language itself, the patent specification, and the prosecution history before the U.S. Patent and Trademark Office — and may consider extrinsic evidence such as dictionaries and expert testimony where the intrinsic record leaves the meaning unsettled. The output is an order assigning a definite meaning to each disputed term. That order then governs how the infringement and invalidity issues are presented to the jury.

Consider a representative claim term. U.S. Patent No. 9,479,428, assigned to Marvell World Trade Ltd., recites a "mesh routing module configured to receive a first packet from a second wireless network device." If two parties disputed whether "module" required dedicated hardware or could read on software running on a general-purpose processor, that single word could decide infringement for an entire product line. A Markman hearing is where that fight is resolved, and it is resolved by the judge reading the claim in light of the specification and prosecution history.

There is no fixed statutory deadline for a Markman hearing. Courts schedule them at varying points, sometimes early in the case and sometimes close to trial, and the timing is set by the district court's local patent rules and the individual judge's practice. Some courts issue a construction on the papers without live argument; others hold a tutorial and a full evidentiary hearing. The Supreme Court in Markman did not prescribe a procedure — it allocated the decision to the court and left the mechanics to the trial judge.

Why a Markman ruling can end the case

Because infringement requires the accused product to meet every limitation of a claim as construed, a single adverse construction can make infringement impossible to prove. Where the construction forecloses the patentee's infringement theory, the case often resolves on summary judgment rather than proceeding to a jury. The same construction also frames validity: a term read broadly may capture more prior art and raise anticipation or obviousness exposure, while a narrow reading may avoid prior art but also narrow the scope of infringement. Parties therefore litigate constructions with the understanding that the wording chosen at the Markman stage can dictate the outcome of the entire dispute.

A claim-construction ruling is reviewed by the U.S. Court of Appeals for the Federal Circuit. Under the Supreme Court's later decision in Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 574 U.S. 318 (2015), the ultimate construction is reviewed de novo, but any subsidiary findings of fact the district court made about extrinsic evidence are reviewed for clear error. That allocation traces directly back to the Markman holding that claim construction belongs to the court — the appellate court reviews the judge's work, not a jury's.

Intrinsic versus extrinsic evidence

The hierarchy of evidence a court uses at a Markman hearing is settled. The Federal Circuit's en banc decision in Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005), instructs that the words of a claim are read in the context of the entire patent, including the specification, and that the specification is the single best guide to the meaning of a disputed term. Prosecution history — the record of what the applicant said to the examiner to obtain the patent — can narrow a claim where the applicant disclaimed coverage. Extrinsic evidence such as treatises, dictionaries, and expert testimony is admissible but is given less weight than the intrinsic record and cannot be used to contradict a meaning the intrinsic record makes clear.

This ordering matters because it constrains the argument a party can make. A litigant cannot rely on an expert's preferred reading of a term if the specification and prosecution history point the other way. At the hearing, much of the dispute therefore reduces to how the specification uses the term and whether the applicant said anything during prosecution that limits it. A judge who finds the intrinsic record clear may never reach the extrinsic evidence at all.

The procedural weight of the Markman ruling also explains why parties invest so heavily in it. Because the construction is reviewed de novo on appeal for its legal component, a party that loses a construction in the district court can challenge it at the Federal Circuit without deferring to the trial judge's reading — but it must first live with that construction through summary judgment and trial. The combination of a potentially case-dispositive ruling and de novo appellate review makes claim construction one of the most consequential, and most litigated, stages of a patent case.