Markman v. Westview Instruments, Inc.
In Markman, the Supreme Court held that the construction of a patent claim is a question of law to be decided exclusively by the court. The decision allocated the central interpretive task of patent litigation to the judge rather than the jury, and gave the trial bench a tool — the claim construction hearing — that has structured every infringement case since.
Holding
The Supreme Court held that the interpretation of a patent claim, including the construction of technical terms used in the claim, is a matter of law reserved for the court. The Seventh Amendment does not require that claim construction be submitted to the jury. The Court affirmed the Federal Circuit's en banc decision below and ratified what the Federal Circuit had described as the patent claim's role as the "metes and bounds" of the patentee's right to exclude.
Procedural posture and facts
Herbert Markman owned U.S. Patent No. 4,550,246, directed to a system for tracking inventory in dry-cleaning establishments. The claims used the term "inventory," and the dispute turned on whether "inventory" referred only to articles of clothing or extended to cash and invoices. Westview Instruments produced a system that tracked transactions and dollar amounts but did not track the location or status of garments in the way Markman's system did.
The case was tried to a jury in the Eastern District of Pennsylvania. The jury returned a verdict for Markman, finding that Westview's product infringed. The district court granted Westview's motion for judgment as a matter of law, ruling that the term "inventory" as used in the claims required tracking articles of clothing and that Westview's product, which tracked only transactions, did not infringe.
The Federal Circuit took the case en banc and affirmed. Markman v. Westview Instruments, Inc., 52 F.3d 967 (Fed. Cir. 1995) (en banc). The en banc court held that claim construction is exclusively for the court, displacing the prior practice in some circuits of letting the jury decide what disputed claim terms meant. The Supreme Court granted certiorari to decide whether the Seventh Amendment compelled a different rule.
The Court's reasoning
Justice Souter, writing for a unanimous Court, addressed the Seventh Amendment question through a two-step analysis that the Court had used before to allocate functions between judge and jury. First, the Court asked whether the issue was one tried to a jury at common law in 1791. Second, where the historical record was inconclusive, the Court asked which actor — judge or jury — was better positioned to perform the function in light of the precedents and functional considerations.
Historical practice
The historical inquiry produced no clear answer. Patent infringement actions were tried at common law in late-eighteenth-century England, and juries did decide infringement. But the Court found no English case from that era that squarely allocated the interpretation of the patent specification to the jury as opposed to the court. The closest analogues — disputes over the meaning of terms in deeds and other written instruments — had long been understood as matters for the judge. The Court declined to read the silence as a constitutional mandate either way.
Functional considerations
Because history was indeterminate, the Court turned to which institution was better suited to construe a patent claim. Three considerations pointed to the judge. First, claim construction is fundamentally an interpretive exercise applied to a written legal instrument — the patent — rather than a factual reconstruction of events. Second, judges have superior training in interpreting written documents and the legal background against which patents issue. Third, treating claim construction as a question of law promotes uniformity: a single patent should mean the same thing in every infringement case it spawns, and only judicial determination subject to de novo appellate review can secure that uniformity.
The Court acknowledged that claim construction often involves understanding technical evidence and the perspective of a person of ordinary skill in the art. But that did not convert the exercise into a jury question; courts routinely receive expert testimony and other evidence to inform legal determinations. The Seventh Amendment guaranteed a jury trial of the underlying factual disputes about literal infringement and validity; it did not guarantee a jury role in deciding what the words of the claim mean.
The framework Markman produced
Markman made claim construction the central pretrial event in nearly every patent case. Three structural changes followed.
Markman hearings
District courts began holding dedicated claim construction hearings, often with live expert testimony, exhibits, and tutorials, to construe disputed claim terms before trial. Local patent rules in the leading patent districts — including the Eastern District of Texas, the Northern District of California, the District of Delaware, and the Western District of Texas — formalized exchange schedules for proposed constructions, joint claim-construction statements, and briefing.
Standard of review on appeal
For nearly two decades after Markman, the Federal Circuit reviewed claim construction de novo in its entirety. Cybor Corp. v. FAS Technologies, Inc., 138 F.3d 1448 (Fed. Cir. 1998) (en banc), confirmed pure de novo review with no deference to subsidiary findings. The result was a high reversal rate on appeal and persistent uncertainty about how a district court's construction would fare on review.
Modification by Teva v. Sandoz
The Supreme Court partially recalibrated the standard in Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 574 U.S. 318 (2015). Teva held that, while the ultimate question of claim construction remains a legal one reviewed de novo, a district court's resolution of subsidiary factual disputes — for example, the meaning of a technical term to a person of ordinary skill in the art based on extrinsic evidence — is reviewed for clear error under Federal Rule of Civil Procedure 52(a)(6). Markman's allocation of the construction itself to the judge survived. What changed was the appellate standard for the historical and technical findings that may underlie that construction.
Subsequent application
The Federal Circuit refined the methodology of claim construction in a long line of cases that culminated in Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (en banc). Phillips ranked the sources of meaning — claims, specification, and prosecution history first, with extrinsic evidence playing a secondary role — but the institutional allocation that Markman produced (judge, not jury) remained fixed.
Markman has also influenced the architecture of post-grant proceedings. The Patent Trial and Appeal Board conducts its own claim construction in inter partes review and post-grant review, and the standard is now the same Phillips standard used in district court. The Board's constructions are reviewed under the substantial-evidence and Chevron-style frameworks applicable to agency adjudications, but the conceptual framework — that someone trained in the law applies the intrinsic record to fix the meaning of a written claim — is Markman's.
In the Federal Circuit, claim construction continues to drive case outcomes. A construction that excludes the accused product moots literal infringement as a matter of law, often before trial. A construction that captures the accused product narrows the trial to factual issues such as the application of equivalents, validity over prior art, and damages.
Open questions and pressure points
Several pressure points remain. First, the line between "ultimate" claim construction and "subsidiary" factual findings under Teva is not always clear, and the Federal Circuit has at times treated extrinsic evidence as background information rather than as a Rule 52(a)(6) finding subject to deference. The result is that the practical reach of Teva varies from panel to panel.
Second, Markman's promise of uniformity is imperfect. Until the Federal Circuit speaks, two district courts can construe the same claim term differently, and parties can shop for a forum or a stage of the case to resecure a favorable construction. Issue preclusion partially addresses serial litigation between the same parties, but it does not generally bind strangers to a prior judgment.
Third, the role of dictionaries, treatises, and expert testimony continues to generate friction. Phillips put extrinsic evidence in its place, but live tutorials and competing expert declarations remain a routine feature of Markman practice. How much weight a court gives extrinsic evidence — and whether that weight survives appellate review — is one of the persistent variables in patent litigation.
Finally, Markman did not resolve all jury-allocation questions in patent cases. Issues of enablement and written description, definiteness, and inequitable conduct have their own jury/judge maps, and those maps have evolved separately. Markman established the core principle — interpretation of the claim is for the court — but the broader question of how much of patent litigation is for the jury continues to be litigated section by section.
Citation and record
Formal citation: Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996).
Below: Markman v. Westview Instruments, Inc., 52 F.3d 967 (Fed. Cir. 1995) (en banc), affirming 772 F. Supp. 1535 (E.D. Pa. 1991).
Author: Justice Souter for a unanimous Court. Argued January 8, 1996; decided April 23, 1996.
Vote alignment: 9-0.
See also
- Claim constructionThe doctrinal framework Markman produced and that Phillips refined.
- Phillips v. AWH Corp.Federal Circuit en banc decision setting the methodology of claim construction.
- Markman hearingsThe pretrial proceeding that grew out of this decision.
- Standards of reviewDe novo review of claim construction, with clear-error review of subsidiary fact findings under Teva.
- Federal Circuit appealsHow claim construction issues are presented and reviewed on appeal.
- Literal infringementThe factual question that follows once the claim is construed.
Last reviewed: 2026