Markman v. Westview Instruments (1996): Who interprets patent claims?

THE JUDGMENT IN ONE SENTENCE Patent claim construction—the judicial determination of what a patent’s claims mean and how far they extend—is a question of law for the judge, not the jury, even when technical terms and expert testimony are involved.

1. Case at a glance

• Item: Case — Details: Markman v. Westview Instruments, Inc.; Positek, Inc. was also a petitioner and Althon Enterprises, Inc. a respondent.
• Item: Citation — Details: 517 U.S. 370 (1996)
• Item: Docket — Details: No. 95-26
• Item: Court / date — Details: Supreme Court of the United States; decided 23 April 1996; argued 8 January 1996.
• Item: Opinion — Details: Justice David H. Souter delivered the opinion for a unanimous Court.
• Item: Patent — Details: U.S. Patent No. 4, known in the opinion as Markman’s patent for an “Inventory Control and Reporting System for Drycleaning Stores.”
• Item: Main legal question — Details: Who decides the meaning of disputed patent claim terms: judge or jury?
• Item: Constitutional provision — Details: Seventh Amendment right to trial by jury.
• Item: Disposition — Details: Federal Circuit judgment affirmed.

2. Why claim construction matters

A patent does not protect every feature or idea mentioned in its description. Its claims define the legal boundaries of the invention. Before a court can decide whether a competing product infringes, it must determine what the disputed claim language means. This interpretive step is called claim construction.

THE CORE DISTINCTION Claim construction asks: “What does the patent claim cover?” Infringement asks: “Does the accused product or method fall within those properly interpreted claims?” The first is for the judge; infringement questions may involve factual determinations for a jury.

This allocation matters because the meaning assigned to a claim term can determine the result of the case. A broad construction may encompass a competing product; a narrower construction may place it outside the patent’s scope.

3. Facts: the dry-cleaning inventory system

Herbert Markman owned a patent for an inventory-control and reporting system intended for dry-cleaning stores. The system used a keyboard and data processor to generate transaction records, including bar-coded tickets that could be read by optical detectors. The claims referred to maintaining an “inventory total” and detecting and locating improper additions to inventory.

Westview Instruments supplied a system that also used a keyboard, processor, and bar-coded tickets. However, the dispute concerned what the system tracked: Markman’s system was said to track clothing moving through the dry-cleaning process, while Westview’s system recorded charges and transaction totals—effectively tracking invoices or receivables rather than the physical garments.

THE DISPUTED WORD: “INVENTORY” Was “inventory” broad enough to include financial records and invoice totals, or did the claim, read in context, refer to the physical articles of clothing being processed by a dry cleaner? The answer affected whether Westview’s system fell within the claim.

4. Procedural history

District court: a jury found that Westview infringed certain claims after hearing testimony about the meaning of the claim language. The judge later entered judgment for Westview, concluding that Westview’s system did not meet the claims as properly construed.

Federal Circuit, sitting en banc: affirmed. It held that interpreting patent claims is the exclusive responsibility of the court.

Supreme Court: unanimously affirmed the Federal Circuit. It held that claim construction, including the interpretation of technical terms within a claim, belongs to the judge.

The Supreme Court was not deciding the technical meaning of every term in every patent. It was deciding who has the authority to construe claims as a matter of law.

5. Legal issue and holding

QUESTION PRESENTED Does the Seventh Amendment require a jury to determine the meaning of disputed technical terms in patent claims when expert testimony is offered, or is claim construction exclusively for the court?

Holding: The construction of a patent, including terms of art within its claims, is exclusively within the province of the court. The Supreme Court found no Seventh Amendment requirement that a jury decide claim meaning.

6. The Court’s reasoning

A. Historical practice and the Seventh Amendment

The Seventh Amendment preserves the civil jury-trial right as it existed under English common law when the Amendment was adopted. The Court considered historical patent practice and found that judges had traditionally construed patent specifications and their terms. Although modern claim construction did not have a perfect historical equivalent, the closest analogues supported judicial interpretation.

B. Existing precedent distinguished interpretation from infringement

The Court relied on the established distinction between construing a patent and determining whether infringement occurred. The former is a question of law for the court; the latter may involve factual questions. The opinion discussed earlier authority, including Winans v. Denmead, which articulated this division.

C. Judges are institutionally suited to interpret patent documents

Patent claims are part of a technical written instrument. The judge must interpret disputed language in the context of the patent as a whole and assess whether proposed meanings fit the document. Experts may assist, but their testimony does not bind the court.

D. Uniformity matters

The same patent should not receive different meanings simply because separate juries hear different infringement cases. Assigning claim construction to judges promotes consistent treatment of a patent’s scope across disputes.

7. How claim construction is performed in practice

Markman establishes who decides claim meaning. Later Federal Circuit precedent—especially Phillips v. AWH Corp. (2005)—developed the modern methodology used to interpret claims. The following process describes the widely used U.S. approach; it should not be mistaken for a verbatim checklist set out in Markman itself.

• Step: 1. Read the claim language — Material considered: The words of the asserted claim, surrounding limitations, grammar, and how terms relate to each other. — Practical question: What do the actual claim words mean in context?
• Step: 2. Read the specification — Material considered: The written description, disclosed embodiments, and any express definition or clear disclaimer. — Practical question: How does the patent explain or use this term?
• Step: 3. Review prosecution history — Material considered: The exchanges with the patent examiner, amendments, arguments, and representations made to obtain the patent. — Practical question: Did the applicant clearly narrow or explain the claim during examination?
• Step: 4. Consider extrinsic evidence if useful — Material considered: Expert testimony, technical dictionaries, treatises, and other evidence outside the patent record. — Practical question: Does outside evidence clarify technical meaning without overriding the intrinsic record?
• Step: 5. State the construction — Material considered: The court resolves material disputes and explains the meaning that will govern the infringement analysis. — Practical question: What construction will the jury or factfinder apply when comparing the accused product with the claim?

KEY INTERPRETIVE PRINCIPLE The claim language is read in the context of the patent as a whole. Expert testimony and dictionaries can help, but they should not displace the meaning supported by the claim, specification, and prosecution history.

8. Intrinsic and extrinsic evidence

• Evidence type: Intrinsic: claims — Examples: Independent and dependent claims; surrounding words and limitations. — Role and caution: Usually the starting point. Claim terms must be understood in their claim context.
• Evidence type: Intrinsic: specification — Examples: Detailed description, drawings, embodiments, definitions. — Role and caution: Often highly informative; do not automatically import a preferred embodiment’s limitations into broader claim language.
• Evidence type: Intrinsic: prosecution history — Examples: Amendments, office-action responses, applicant arguments and disclaimers. — Role and caution: Can show how the applicant explained or narrowed the invention; read with care and in context.
• Evidence type: Extrinsic: expert testimony — Examples: Technical explanations from people knowledgeable in the relevant field. — Role and caution: May explain background technology or technical terms; the judge is not required to accept an expert’s proposed construction.
• Evidence type: Extrinsic: dictionaries / treatises — Examples: General or technical dictionaries, technical publications. — Role and caution: May assist with ordinary or technical meaning, but should not override clear intrinsic evidence.

Terminology note: the intrinsic/extrinsic evidence framework is explained in detail in later Federal Circuit case law, particularly Phillips. Markman itself supports judicial interpretation of the patent document as a whole and permits the court to use expert assistance without surrendering its interpretive responsibility.

9. Worked example: construing “inventory”

• Stage: Term in dispute — Application to the dispute: “Inventory”
• Stage: Possible broad reading — Application to the dispute: Records of financial items, invoices, charges, or receivables.
• Stage: Possible narrower reading — Application to the dispute: Physical garments tracked as they enter, move through, and leave the dry-cleaning process.
• Stage: Evidence to examine — Application to the dispute: The full claim language; how “inventory” is used elsewhere in the patent; the specification’s description of the system; drawings and disclosed operation; prosecution statements; and technical evidence where needed.
• Stage: Construction decision — Application to the dispute: The judge determines the legally controlling meaning after examining the record—not by simply asking the jury which meaning seems more natural.
• Stage: Infringement comparison — Application to the dispute: The factfinder then compares the accused system with each limitation of the claim as construed. If a required limitation is absent, literal infringement is not established on that basis.

WHY THIS EXAMPLE IS USEFUL A single disputed term can determine the boundary of the patent. Claim construction is therefore not a dictionary exercise alone; it is a contextual legal interpretation of the patent and its prosecution record.

10. Judge versus jury: who decides what?

• Issue: Meaning and scope of disputed patent claims — Primary decision-maker: Judge — Reason: Claim construction is a question of law under Markman.
• Issue: Underlying factual disputes relevant to construction — Primary decision-maker: Judge evaluates the evidence; some subsidiary factual findings may arise depending on the method used. — Reason: Later doctrine, including Teva Pharmaceuticals v. Sandoz (2015), addresses appellate review of subsidiary factual findings underlying claim construction.
• Issue: Whether the accused product meets the construed claim limitations — Primary decision-maker: Often jury where a jury trial is available, subject to the case’s procedural posture and applicable law. — Reason: This is the infringement comparison, distinct from deciding what the claim means.
• Issue: Expert explanation of technical terminology — Primary decision-maker: Expert assists; judge retains final interpretive authority. — Reason: Expert testimony is evidence, not a delegation of the legal decision.

11. Why the decision is important

Predictability: a patent’s claims should have a consistent meaning across different infringement disputes.

Efficient trial structure: the court can resolve claim meaning before the factfinder considers infringement under the construction.

Technical interpretation: judges can evaluate expert evidence against the patent document as a whole.

Strategic importance: the construction of one key term may determine whether an accused product falls within the patent.

Patent drafting: applicants should define key terms clearly, maintain consistency between claims and specification, and avoid unintended ambiguity.

Litigation strategy: parties should identify disputed terms early, propose precise constructions, and tie each proposal to intrinsic evidence rather than relying only on a preferred expert opinion.

12. Relationship with later cases

• Case: Markman v. Westview, 517 U.S. 370 (1996) — Contribution: Allocates claim construction to the judge as a question of law. — How it relates: The foundational judge-versus-jury rule.
• Case: Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (en banc) — Contribution: Emphasizes claim language, specification, and prosecution history in construing claims; treats extrinsic evidence as less authoritative. — How it relates: Provides the principal modern methodology for how claims are construed.
• Case: Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 574 U.S. 318 (2015) — Contribution: Explains that subsidiary factual findings underlying claim construction are reviewed for clear error, while the ultimate legal construction is reviewed de novo. — How it relates: Refines the appellate standard of review without overturning Markman’s core allocation.

13. Ratio decidendi

RULE OF LAW The interpretation and construction of patent claims—including disputed technical terms within them—is a matter of law reserved to the court, not the jury. Historical practice, the judge’s role in interpreting written instruments, and the need for uniformity support that allocation. Expert evidence may assist the judge but does not transfer the ultimate interpretive decision to the jury.

14. What Markman does not mean

It does not mean juries have no role in patent infringement cases; juries may determine infringement-related facts under the court’s construction.

It does not mean judges must ignore expert testimony or technical dictionaries.

It does not mean every disputed word should be rewritten or given a special technical definition; some terms may carry their ordinary meaning in context.

It does not make claim construction a free-form policy exercise: the court must interpret the claim in the context of the patent record and applicable law.

It does not itself set out every detail of the modern claim-construction methodology; later cases, especially Phillips, developed that approach.

15. Conclusion

Markman v. Westview Instruments is a foundational patent-law decision because it assigns claim construction to the judge. The Court reasoned that claim meaning is a legal interpretation of a technical written instrument and that a consistent construction promotes fairness and uniformity. The jury’s role in an infringement case remains important, but it operates against the legal meaning established by the court.

The practical lesson is straightforward: before asking whether a product infringes, the court must establish what the patent claim requires. That construction is made by examining the claim language in context, the specification and prosecution history, with appropriate assistance from technical evidence where needed.

16. Primary sources and further reading

Supreme Court opinion — Justia, Markman v. Westview Instruments, 517 U.S. 370 (1996) https://supreme.justia.com/cases/federal/us/517/370/

Official U.S. Reports record — GovInfo https://www.govinfo.gov/app/details/USREPORTS-517/USREPORTS-517-370

Cornell Legal Information Institute — full Supreme Court opinion https://www.law.cornell.edu/supremecourt/text/517/370

Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (en banc) https://law.justia.com/cases/federal/appellate-courts/cafc/04-1171/04-1171-2011-03-27.html

Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 574 U.S. 318 (2015) https://supreme.justia.com/cases/federal/us/574/318/

Research note: This educational case study distinguishes the Supreme Court’s holding in Markman from later claim-construction methodology developed in Phillips and subsequent cases. It is not legal advice and focuses on U.S. patent law.

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