In Markman v. Westview Instruments, 517 U.S. 370 (1996), the Supreme Court unanimously held that interpreting the words of a patent claim is a question of law for the judge, not a factual question for the jury. That single ruling reorganized patent litigation around a new pretrial event, the Markman hearing, where a judge fixes the meaning of the disputed patent terms before a jury ever hears about infringement.
The Fight Over a Single Word
Herbert Markman held U.S. Reissue Patent No. 33,054 on a system for monitoring clothing moving through a dry-cleaning business. The system combined a keyboard, a data processor, and bar-code readers so employees could log each garment’s progress and generate transaction records.
Westview Instruments sold a device that also performed tracking functions for dry cleaners, and Markman sued for infringement. The case came down to one word in his claims: “inventory.” Markman argued the term covered both the physical clothing and the financial data from transactions. Westview said its product only tracked cash-register data, not individual garments, and so fell outside the patent. The trial court construed “inventory” to include both articles of clothing and cash-register figures, a reading that sank Markman’s case because Westview’s system did not track clothing through the cleaning process and therefore did not infringe under that definition.1Justia Law. Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996)
What reached the Supreme Court was not really about dry cleaning. It was about who gets to decide what a patent’s words mean in the first place.
The Seventh Amendment Question
Before Markman, no clear rule told courts whether a judge or a jury should define patent claim terms. The Seventh Amendment preserves the right to a jury trial in civil suits where the amount in controversy exceeds twenty dollars, and patent infringement cases easily clear that bar.2Legal Information Institute. Constitution Annotated – Amendment 7 – Restrictions on the Role of the Judge Patent holders argued that figuring out what a technical term means is a factual inquiry, the kind of question juries are supposed to handle after weighing expert testimony.
The competing view treated patents the way courts treat contracts and deeds: as written legal instruments whose meaning is for a judge to resolve. Proponents of judicial control warned that different juries in different courtrooms could read the same patent and reach opposite conclusions, making patent rights unpredictable and undermining the investment the patent system exists to encourage.
What the Supreme Court Held
The Court ruled unanimously that claim construction belongs to the court. Justice Souter wrote that patent claim construction is “a matter of law reserved entirely for the court” and is not “subject to a Seventh Amendment guarantee that a jury will determine the meaning of any disputed term of art about which expert testimony is offered.”3Supreme Court of the United States. Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996)
The opinion rested on two practical grounds. First, judges are trained in interpreting written documents. The Court quoted an 1849 decision for the proposition that patent construction “is a special occupation, requiring, like all others, special training and practice,” and that a judge “is more likely to give a proper interpretation to such instruments than a jury.”3Supreme Court of the United States. Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996) Second, the Court emphasized uniformity. If judges construe the same patent the same way from one court to the next, patent owners and competitors can predict their rights without relitigating identical questions.
What the Jury Still Does
Markman did not push juries out of patent trials. Once the judge defines what the patent terms mean, the jury decides whether the accused product actually meets those definitions and therefore infringes. Jurors cannot substitute their own reading of the patent language for the judge’s construction during deliberations. Judge interprets the patent; jury applies that interpretation to the facts. That division is now the organizing principle of every patent trial.
The Markman Hearing
The practical consequence of the ruling is a specialized pretrial proceeding now standard in patent cases. Markman hearings typically happen after discovery but before trial, though the exact timing is within the district judge’s discretion. Both sides submit briefs identifying the claim terms they consider disputed and proposing their preferred definitions.
At the hearing, attorneys argue from the patent’s text, its specification, and its prosecution history. When the technology is complex enough that those sources do not resolve the dispute, judges may hear live testimony from technical experts, and some appoint independent technical advisors to help them understand the science. A hearing can last from a few hours to several days depending on how many terms are in dispute and how technically dense the patent is.
Afterward, the judge issues a claim construction order: a written ruling that provides binding definitions for every disputed term. Both sides must use those definitions at trial, in motions, and in any further proceedings. Jurors hear only the judge’s definitions, not the competing proposals the parties originally offered.
Why the Hearing Often Decides the Case
A Markman ruling frequently determines the outcome long before a jury is seated. When the judge’s construction of a key term aligns closely with one side’s position, the other side may face an infringement case that is almost impossible to win or defend. In those situations, the disadvantaged party often settles, or the winning party moves for summary judgment on the ground that the claim construction leaves no genuine factual dispute.
That is why experienced patent litigators pour resources into claim construction briefing. The definitions a judge selects can render an otherwise strong infringement theory dead on arrival, and a favorable construction can transform a marginal case into a near-certain winner.
Appeals After Markman
Claim construction rulings can be appealed to the U.S. Court of Appeals for the Federal Circuit, which has exclusive jurisdiction over patent appeals. For nearly two decades after Markman, the Federal Circuit reviewed every claim construction decision without any deference to the trial judge, applying a purely de novo standard. Studies from that period found the court overturned at least one claim term in roughly 37% of appealed cases.
The Supreme Court adjusted the standard in Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 574 U.S. 318 (2015). It held that when a district judge resolves factual disputes about extrinsic evidence during claim construction, such as choosing between competing expert interpretations of a scientific term, the appellate court must defer to those factual findings unless they are clearly erroneous. The ultimate legal conclusion about what a claim term means is still reviewed de novo, but the underlying factual building blocks receive the same protection as factual findings in any other kind of case.4Justia Law. Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 574 U.S. 318 (2015)
In practice, a claim construction based entirely on the patent’s text, specification, and prosecution history is still fully reviewable on appeal, because those are legal determinations. When a judge had to rely on expert testimony to understand the technology and made factual findings in the process, the Federal Circuit can only overturn those findings by identifying clear error.4Justia Law. Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 574 U.S. 318 (2015)
How Markman Reshaped Patent Litigation
Before 1996, claim meaning was tangled up with infringement questions, and parties could not know until a jury verdict whether their reading of a patent would prevail. Pulling claim construction out of the jury’s hands created a discrete, early decision point that gives both sides clarity long before the expense of a full trial. Patent holders now draft claims with an eye toward how a judge will later construe them, and defendants dig through prosecution history and specification language for anything that narrows the patent’s reach. Claim construction has become the main event in most patent disputes, and the trial itself sometimes feels like a formality once the judge’s definitions are locked in.