Markman v. Westview Instruments, Inc.,
517 U.S. 370 (1996)

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No. 95-26. Argued January 8, 1996-Decided April 23, 1996

Petitioner Markman owns the patent to a system that tracks clothing through the dry-cleaning process using a keyboard and data processor to generate transaction records, including a bar code readable by optical detectors. According to the patent's claim, the portion of the patent document that defines the patentee's rights, Markman's product can "maintain an inventory total" and "detect and localize spurious additions to inventory." The product of respondent Westview Instruments, Inc., also uses a keyboard and processor and lists dry-cleaning charges on bar-coded tickets that can be read by optical detectors. In this infringement suit, after hearing an expert witness testify about the meaning of the claim's language, the jury found that Westview's product had infringed Markman's patent. The District Court nevertheless directed a verdict for Westview on the ground that its device is unable to track "inventory" as that term is used in the claim. The Court of Appeals affirmed, holding the interpretation of claim terms to be the exclusive province of the court and the Seventh Amendment to be consistent with that conclusion.

Held: The construction of a patent, including terms of art within its claim, is exclusively within the province of the court. Pp. 376-391.

(a) The Seventh Amendment right of trial by jury is the right which existed under the English common law when the Amendment was adopted. Baltimore & Carolina Line, Inc. v. Redman, 295 U. S. 654, 657. Thus, the Court asks, first, whether infringement cases either were tried at law at the time of the founding or are at least analogous to a cause of action that was. There is no dispute that infringement cases today must be tried before a jury, as their predecessors were more than two centuries ago. This conclusion raises a second question: whether the particular trial issue (here a patent claim's construction) is necessarily a jury issue. This question is answered by comparing the modern practice to historical sources. Where there is no exact antecedent in the common law, the modern practice should be compared to earlier practices whose allocation to court or jury is known, and the


best analogy that can be drawn between an old and the new must be sought. Pp. 376-378.

(b) There is no direct antecedent of modern claim construction in the historical sources. The closest 18th-century analogue to modern claim construction seems to have been the construction of patent specifications describing the invention. Early patent cases from England and this Court show that judges, not juries, construed specification terms. No authority from this period supports Markman's contention that even if judges were charged with construing most patent terms, the art of defining terms of art in a specification fell within the jury's province. Pp. 378-384.

(c) Since evidence of common-law practice at the time of the framing does not entail application of the Seventh Amendment's jury guarantee to the construction of the claim document, this Court must look elsewhere to characterize this determination of meaning in order to allocate it as between judge or jury. Existing precedent, the relative interpretive skills of judges and juries, and statutory policy considerations all favor allocating construction issues to the court. As the former patent practitioner, Justice Curtis, explained, the first issue in a patent case, construing the patent, is a question of law, to be determined by the court. The second issue, whether infringement occurred, is a question of fact for a jury. Winans v. Denmead, 15 How. 330, 338. Contrary to Markman's contention, Bischoff v. Wethered, 9 Wall. 812, and Tucker v. Spalding, 13 Wall. 453, neither indicate that 19th-century juries resolved the meaning of patent terms of art nor undercut Justice Curtis's authority. Functional considerations also favor having judges define patent terms of art. A judge, from his training and discipline, is more likely to give proper interpretation to highly technical patents than a jury and is in a better position to ascertain whether an expert's proposed definition fully comports with the instrument as a whole. Finally, the need for uniformity in the treatment of a given patent favors allocation of construction issues to the court. Pp.384-391.

52 F.3d 967, affirmed.

SOUTER, J., delivered the opinion for a unanimous Court.

William B. Mallin argued the cause for petitioners.

With him on the briefs were Timothy P. Ryan, Timothy S. Coon, Lewis F. Gould, Jr., and Stephan P. Gribok.

Full Text of Opinion

Primary Holding

Judges, rather than juries, are responsible for determining the meaning of the words in patent claims. They should use the following four sources, in order of importance: the written description, the documentation of the patent during the process, English dictionaries, and expert testimony.


Markman's patent for an Inventory Control and Reporting System for Drycleaning Stores described a system that was designed to monitor and report the status and location of clothing within a store. The system used in drycleaning stores owned by Westview Instruments tracked only invoices rather than clothes. In the ensuing patent infringement action brought by Markham, the parties debated whether the reference to "inventory" in Markham's patent covered cash or clothes. After the jury ruled for Markham, the judge granted Westview's motion for judgment as a matter of law. On appeal, Markham asserted that the Seventh Amendment gave the jury the exclusive authority to interpret the patent claim.



  • David H. Souter (Author)
  • William Hubbs Rehnquist
  • John Paul Stevens
  • Sandra Day O'Connor
  • Anthony M. Kennedy
  • Antonin Scalia
  • Clarence Thomas
  • Ruth Bader Ginsburg
  • Stephen G. Breyer

Juries may not be allowed to determine every issue in a legal action, but only those that it must decide in order to preserve the substantive right to a trial by jury. Since patent claim construction and interpretation is not a traditional area of the law, the best analogy is the interpretation of terms in a land patent, which historically was reserved for the judge rather than the jury. In general, the laypeople who comprise most juries are not equipped to make determinations about these technical terms, and judges are better situated to interpret them. Doing so also would promote the interests of uniformity.

Case Commentary

When clashing experts testify, their relative credibility is sometimes an issue in determining what certain terms of a patent application mean. A jury usually is required for matters of credibility, but the Court was not concerned about this issue in the context of patents.

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