concurring in the judgment.
Today the court jettisons more than two hundred years of jurisprudence and eviscerates the role of the jury preserved by the Seventh Amendment of the Constitution of the United States; it marks a sea change in the course of patent law that is nothing short of bizarre. Sadly, this decision represents a secession from the mainstream of the law. It portends turbulence and cynicism in patent litigation. For this is not just about claim language, it is about ejecting juries from infringement eases. All these pages and all these words cannot camouflage what the court well knows: to decide what the claims mean is nearly always to decide the case.
But today’s action is of a piece with a broader bid afoot to essentially banish juries from patent cases altogether. If it succeeds juries will be relegated, in those few cases where they have any presence at all, to rubber stamps, their verdicts preordained by “legal” and “equitable” determinations that brook only one “reasonable” result. Indeed, this movement would vest authority over patent disputes in legislative courts, unconstrained by Article III and the Seventh Amendment. See In re Lockwood, 50 F.3d 966, 970 (Fed.Cir.1995) (opinion dissenting from order denying rehearing in banc) (“A constitutional jury right to determine validity of a patent does not attach to this public grant. Congress could place the issue of validity entirely in the hands of an Article I trial court with particular expertise if it chose to do so.”). Declaiming that the jury is a “black box” incapable of a “reasoned decision”, several judges of the court have already advised that they are aboard this campaign. Id., at 990. The quest to free patent litigation from the “unpredictability” of jury verdicts, and generalist judges, results from insular dogmatism inspired by unwarrantable elitism; it is unconstitutional.
The question is whether the interpretation of patent claims is a purely legal exercise— always decided by the judge as a matter of law and never raising a question of fact — or rather a mixed question of law and fact, in which some factual matters might need to be resolved by the factfinder on the way to construing the claims as a matter of law. The answer is critical to how questions of claim interpretation are decided at the trial level and how we review them on appeal.
The ultimate issue of patent scope, depending as it does on the legal effect of the words of the claims, is a question of law. But it does not necessarily follow that the judge is to decide every question that arises during the course of claim construction as a matter of law. Cf. Graham v. John Deere Co., 383 U.S. 1, 17, 86 S.Ct. 684, 693, 15 L.Ed.2d 545 (1966) (obviousness is a legal conclusion with underlying factual determinations).1 Instead, characterization of claim construction as “legal” begs the questions whether fact issues may arise subsidiary to the ultimate legal conclusion, how such issues are to be decided, and by whom.
Contrary to what it says today, this court (including the judges in the majority) has always held that claim interpretation is a matter of law depending on underlying factual inquiries. See, e.g., Arachnid Inc. v. Medalist Mktg. Corp., 972 F.2d 1300, 1302, 23 *990USPQ2d 1946, 1948 (Fed.Cir.1992) (though claim construction is issue of law for the court, it “may require the factfinder to resolve certain factual issues such as what occurred during the prosecution history”); Lemelson v. General Mills Inc., 968 F.2d 1202, 1206, 23 USPQ2d 1284, 1288 (Fed.Cir.1992) (same, noting that “underlying factual issues in dispute become the jury’s province to resolve in the course of rendering its verdict on infringement”); Johnston v. IVAC Corp., 885 F.2d 1574, 1579, 12 USPQ2d 1382, 1386 (Fed. Cir.1989) (“A disputed issue of fact may, of course, arise in connection with interpretation of a term in a claim if there is a genuine evidentiary conflict created by the underlying probative evidence pertinent to the claim’s interpretation. However, without such evi-dentiary conflict, claim interpretation may be resolved as an issue of law by the court....” (citation omitted)); see also Tol-O-Matic Inc. v. Proma Produkt-Und Mktg., 945 F.2d 1546, 1552, 20 USPQ2d 1332, 1338 (Fed.Cir.1991) (substantial evidence supported jury’s presumed fact findings on disputed terms and prosecution history); Smithkline Diagnostics Inc. v. Helena Lab. Corp., 859 F.2d 878, 885, 8 USPQ2d 1468, 1474 (Fed.Cir.1988) (fact findings on disputed prosecution history clearly erroneous); Perini America v. PCM Co., 832 F.2d 581, 586, 4 USPQ2d 1621, 1625 (Fed.Cir.1987) (in bench trial, court’s interpretation of disputed claim terms not clearly erroneous); Tillotson Ltd. v. Walbro Corp., 831 F.2d 1033, 1039, 4 USPQ2d 1450, 1454 (Fed.Cir.1987) (vacating summary judgment where construction turns on factual disputes arising from specification, prosecution history, and industry practice); Tandon Corp. v. ITC, 831 F.2d 1017, 1021, 4 USPQ2d 1283, 1286 (Fed.Cir.1987) (Commission’s findings on prosecution history and meaning of terms supported by substantial evidence); H.H. Robertson Co. v. United Steel Deck Inc., 820 F.2d 384, 389, 2 USPQ2d 1926, 1929 (Fed.Cir.1987) (in bench trial, court’s fact findings on claim terms not clearly erroneous); Howes v. Medical Components Inc., 814 F.2d 638, 646, 2 USPQ2d 1271, 1275 (Fed.Cir.1987) (vacating summary judgment because of fact issues surrounding prosecution history); Moeller v. Ionetics, Inc., 794 F.2d 653, 657, 229 USPQ 992, 995 (Fed.Cir.1986) (vacating summary judgment where terms create underlying fact dispute); Palumbo v. Don-Joy Co., 762 F.2d 969, 976, 226 USPQ 5, 9 (Fed.Cir.1985) (vacating summary judgment where fact question of equivalents of “means plus function” claim disputed); Bio-Rad Lab., Inc. v. Nicolet Instrument Corp., 739 F.2d 604, 614, 222 USPQ 654, 662 (Fed.Cir.1984) (substantial evidence supported jury interpretation of disputed terms); McGill Inc. v. John Zink Co., 736 F.2d 666, 675, 221 USPQ 944, 951 (Fed.Cir. 1984) (reversing jury verdict where construction premised on facts not supported by substantial evidence). So it is remarkable that the court so casually changes its collective mind, especially when the just cited precedent was compelled by the Seventh Amendment and not the mere preference of a sufficient number of judges.2 The court’s revisionist reading of precedent to loose claim interpretation from its factual foundations will have profoundly negative consequences for the well-established roles of trial judges, juries, and our court in patent eases.
. I.
Anyone who wants to know what a patent protects must first read its claims, for they are the measure of its scope. Aro Mfg. Co. v. Convertible Top Replacement Co., 365 U.S. 336, 339, 81 S.Ct. 599, 601, 5 L.Ed.2d 592 (1961). Claim language does not exist in a vacuum; it must be understood by reference to the documents annexed to the patent grant, including the specification, of which the claims are a part, and any drawings. Autogiro Co. of Am. v. United States, 384 *991F.2d 391, 397, 181 Ct.Cl. 55, 155 USPQ 697, 702 (1967). The prosecution history often proves useful in determining a patent’s scope, for it reveals the course of dealing with the Patent Office, which may show a particular meaning attached to the terms, or a position taken by the applicant to ensure that the patent would issue. Graham v. John Deere Co., 383 U.S. at 33, 86 S.Ct. at 701. These documents are always available during the course of claim interpretation; they are not extrinsic evidence, though some opinions so characterize them, because they are essentially incorporated into the patent itself.
Patents are directed to those skilled in the art. The task of determining just what the claims mean to skilled artisans falls, in the first instance, to the court. But if, after consideration of all of this documentation, the judge cannot readily resolve the meaning of the claims, he resorts to extrinsic evidence to shed light on them. Moeller, 794 F.2d at 657, 229 USPQ at 995 (trial judge’s failure to allow expert testimony was abuse of discretion). This evidence, in the form of prior art documentary evidence or expert testimony, can show what the claims would mean to those skilled in the art. The content of the prior art and the testimony of technical experts can reveal how others use and understand technical terms that may appear ambiguous or opaque to the judge, who rarely has the knowledge of those skilled in the field of the patent. The inventor himself may qualify as an expert and testify what his claims would mean in the relevant art.3 The judge can even advert to the testimony of patent law experts — that is, patent lawyers— for advice on the interpretation of claims.4 If this information clarifies the meaning of the claims and is uncontested, the judge may rule as a matter of law.
But sometimes extrinsic evidence results in a genuine dispute over the meaning of a term or an event during prosecution.5 When that happens, it falls to the finder of fact to settle it. Lemelson, 968 F.2d at 1206, 23 USPQ2d at 1288; Tol-O-Matic Inc. v. Proma Produkt-Und Mktg., 945 F.2d at 1550, 20 USPQ2d at 1336; Smithkline Diagnostics Inc. v. Helena Lab. Corp., 859 F.2d at 882, 8 USPQ2d at 1472; Palumbo v. Don-Joy Co., 762 F.2d at 974, 226 USPQ at 8.
When a question of claim construction arrives here on appeal, this court reviews the ultimate construction given the claims under the de novo standard applicable to all legal conclusions. But any facts found in the course of interpreting the claims must be subject to the same standard by which we review any other factual determinations: for clear error in facts found by a court; for substantial evidence to support a jury’s verdict. Fed.R.Civ.P. 52(a); Perini America v. PCM Co., 832 F.2d at 584, 4 USPQ2d at 1624; McGill Inc. v. John Zink Co., 736 F.2d at 672, 221 USPQ at 948.
This standard recognizes the jury’s important role in making factual determinations, *992and the role of the trial court as the primary decisionmaker in bench trials. A trial is “the ‘main event’ ... rather than a ‘tryout on the road.’ ” Anderson v. City of Bessemer City, 470 U.S. 564, 575, 105 S.Ct. 1504, 1512, 84 L.Ed.2d 518 (1985). By broadly proclaiming all aspects of claim interpretation to be legal, the court today usurps a major part of the functions of both trial judge and jury in patent cases, obliterating the traditional, defined differences between the roles of judge and jury, and trial and appellate courts.
II.
Beyond any policy argument supporting the traditional roles of judge and jury in patent cases, the court’s decision today flies in the face of the constitutional right to a jury promised by the Seventh Amendment of the Constitution. That promise, “[i]n suits at common law, where the value in controversy shall exceed twenty dollars, the right of trial by jury shall be preserved,” protects litigants’ right to a jury trial where legal, as opposed to equitable, causes are to be determined. Chauffers, Teamsters & Helpers Local No. 391 v. Terry, 494 U.S. 558, 564, 110 S.Ct. 1339, 1344, 108 L.Ed.2d 519 (1990). The amendment does not create an independent right to trial by jury but gives parties rights equivalent in scope to those that existed at common law, in England in 1791, when the Bill of Rights was ratified. Tull v. United States, 481 U.S. 412, 417, 107 S.Ct. 1831, 1835, 95 L.Ed.2d 365 (1987). It does not stop there, however; it extends as well to statutory actions subsequently created by Congress if they are analogous to actions decided in the law courts of eighteenth century England. Id.
The Seventh Amendment does not guarantee the right to have a jury decide all issues in a case. It properly resolves only factual questions, while legal matters are for the court. Even within the realm of factual questions, whether a particular question must always go to the jury depends “on whether the jury must shoulder this responsibility as necessary to preserve the ‘substance of the common-law right of trial by jury.’ ” Id. at 426,107 S.Ct. at 1840 (quoting Colgrove v. Battin, 413 U.S. 149, 152, 93 S.Ct. 2448, 2450, 37 L.Ed.2d 522 (1973)). The Seventh Amendment was intended not to formalize any particular rigid procedural rules, but “to preserve the basic institution of trial by jury in only its most fundamental elements_” Parklane Hosiery Co. v. Shore, 439 U.S. 322, 337, 99 S.Ct. 645, 658, 58 L.Ed.2d 552 (1979) (quoting Galloway v. United States, 319 U.S. 372, 392, 63 S.Ct. 1077, 1088, 87 L.Ed. 1458 (1943)); see also Baltimore & Carolina Line, Inc. v. Redman, 295 U.S. 654, 657, 55 S.Ct. 890, 891, 79 L.Ed. 1636 (1935) (“particularly to retain the common-law distinction between the province of the court and that of the jury”). But where a particular issue goes to these “fundamental elements” or the “substance of the common-law right of trial by jury,” no court may constitutionally remove it from the jury. See Walker v. New Mexico & So. Pac. R. Co., 165 U.S. 593, 596, 17 S.Ct. 421, 422, 41 L.Ed. 837 (1897) (Seventh Amendment “requires that questions of fact in common law actions shall be settled by a jury, and that the court shall not assume directly or indirectly to take from the jury or to itself such prerogative.”); see also Granfinanciera S.A. v. Nordberg, 492 U.S. 33, 51, 109 S.Ct. 2782, 2795, 106 L.Ed.2d 26 (1989) (even Congress “lacks the power to strip parties contesting matters of private right of their constitutional right to a trial by jury.”). The court’s action in this case does just that.
An action for patent infringement is one that would have been heard in the law courts of old England. See, e.g., Bramah v. Hardcastle, 1 Carp.P.C. 168 (K.B.1789), reprinted in I Decisions on the Law of Patents for Inventions 51, 53 (Benjamin V. Abbott ed.) (1887) [hereinafter Abbott] (jury trial of infringement action; jury instructed that patent was invalid, but jury verdict for plaintiff not disturbed); Morris v. Bramsom, 1 Carp. P.C. 30 (K.B.1776), reprinted in Abbott, supra, at 21 (jury trial of infringement action); see also Boulton v. Bull, 1 Carp P.C. 117 (C.P.1795), reprinted in Abbott, supra, at 59, 74 (“[I]nfringement or not, is a question for the jury; in order to decide this case, they must understand the nature of the improvement or thing infringed_”). In this country, a jury trial has always been available in patent cases where damages are sought. In*993deed, the first Patent Act, in 1790, expressly provided that a patent owner was entitled to “such damages as shall be assessed by a jury.” Act of April 10, 1790, ch. 7, § 4, 1 Stat. 109. In such'" eases, the jury has been entrusted with ruling on the ultimate question of infringement, as well as any factual disputes that arise subsidiary to the determination of the legal question of patent validity.
Not infrequently, the ultimate question of infringement, indisputably a matter for the jury, is effectively dictated by the construction given the patent claims. This happens, of course, when the judge affirmatively takes the question from the jury by granting summary judgment or judgment as a matter of law, as it did here; it can also occur when, even though the judge sends the question to the jury, his interpretation of the claims forces the jury’s decision on infringement. That is to say, choosing between contending interpretations of a claim can decide the matter of infringement for all intents and purposes. Our constitutional mandate to preserve the right to jury trial therefore demands that we view any intrusion on the jury’s role in deciding infringement with deep suspicion. See Dimick v. Schiedt, 293 U.S. 474, 486, 55 S.Ct. 296, 301, 79 L.Ed. 603 (1935) (“Maintenance of the jury as a fact-finding body is of such importance and occupies so firm a place in our history and jurisprudence that any seeming curtailment of the right to a jury trial should be scrutinized with utmost care.”).
Today’s decision also threatens to do indirectly what we have declined to do directly, that is, create a “complexity exception” to the Seventh Amendment for patent cases. See SRI Int’l v. Matsushita Elec. Corp. of Am., 775 F.2d 1107, 1130, 227 USPQ 577, 592 (Fed.Cir.1985) (Markey, C.J., additional views). But there is simply no reason to believe that judges are any more qualified than juries to resolve the complex technical issues often present in patent cases. Id. at 1128 & n. 7, 227 USPQ at 591 & n. 7. Indeed, the effect of this case is to make of the judicial process a charade, for notwithstanding any trial level activity, this court will do pretty much what it wants under its de novo retrial. We have consistently stressed that the same rules apply to patent eases as apply to all other civil disputes. Connell v. Sears, Roebuck & Co., 722 F.2d 1542, 1547, 220 USPQ 193, 197 (1983) (“So long as the Seventh Amendment stands, the right to a jury trial should not be rationed, nor should particular issues in particular types of cases be treated differently from similar issues in other types of cases.”). The court subverts this principle and the demands of the Seventh Amendment by the ruse of reclassifying factual questions as legal ones.
III.
Those who argue for interpretation of claims solely as a matter of law by the judge spew a panoply of cases ostensibly in support. Close examination of these eases, however, reveals that, like the one before us today, interpretation of the claims at issue before the deciding court presented no real factual question. Thus, for example, in Hogg v. Emerson, 47 U.S. (6 How.) 437, 484, 12 L.Ed. 505 (1848), the Court stated that “without the aid of experts and machinists, [we have] no difficulty in ascertaining, from the language used here,” the meaning of the patent. Similarly, Winans v. New York & Erie R.R. Co., 62 U.S. (21 How.) 88, 100, 16 L.Ed. 68 (1858), allowed the possibility that “experts may be examined to explain terms of art,-and the state of the art at any given time. They may explain to the court and jury the machines, models, or drawings exhibited.” But the Court went on to say that there was only one construction of the patent “which the language of this specification will admit” and “it would be wholly superfluous to examine experts to teach the court, what' they could clearly perceive without such information.” Id., 62 U.S. at 101. Brown v. Piper, 91 U.S. 37, 41, 23 L.Ed. 200 (1847), recognized that evidence on “what was old and in general use at the time of the alleged invention” was admitted at the trial but that it was unnecessary. “[W]e think the patent was void on its face, and that the court might have stopped short at that instrument, and without looking beyond it into the answers and testimony, sua sponte, if objection were not taken by counsel, well have adjudged in favor of the defendant.” Id., 91 U.S. at 44. *994See also U.S. Indus. Chem., Inc. v. Carbide & Carbon Chem. Corp., 315 U.S. 668, 677, 62 5.Ct. 839, 844, 86 L.Ed. 1105 (1942) (“[0]n the face of the papers, the process described in the original patent included a step [omitted from the reissue],” and the trial court erroneously relied on unnecessary expert opinion in its improper conclusion that the reissue was not invalid.); Exhibit Supply Co. v. Ace Corp., 315 U.S. 126, 134, 62 S.Ct. 513, 518, 86 L.Ed. 736 (1942) (“examination of the drawings and specifications indicates clearly enough” the meaning of the claim); Smith v. Snow, 294 U.S. 1, 14, 55 S.Ct. 279, 284, 79 L.Ed. 721 (1935) (“Examination of the claim, in light of both [undisputed] scientific fact and of the particular form in which the petitioner reduced the claim to practice as described in the specifications, makes it plain” what are the claim’s relevant limitations.).
These cases simply do not address the effect of extrinsic evidence giving rise to a legitimate fact question. They are cases where the documentary record alone was wholly adequate to derive the patent’s proper construction.6 It is hardly surprising that courts would treat claim interpretation under these circumstances as a matter of law, for it could not be otherwise. See Fed.R.Civ.P. 50(a) (court may grant judgment as a matter of law where underlying facts could not support reasonable jury verdict to the contrary), and 56(c) (summary judgment appropriate where there, is no genuine issue as to any material fact); Newell Companies, Inc. v. Kenney Mfg. Co., 864 F.2d 757, 762, 763, 9 USPQ2d 1417, 1421-22 (1988) (approving use of judgment as a matter of law and summary judgment on obviousness where underlying facts are not disputed).
Indeed, some cases cited in support of a purported rule that claim construction is always entirely a matter of law expressly limit the rule to those cases where the patent may be understood on the basis of the documents alone, without resort to extrinsic evidence; these eases acknowledge that fact questions could be raised that would require submission to a jury. In Heald v. Rice, 104 U.S. 737, 749, 26 L.Ed. 910 (1881), the Supreme Court explained:
That is, if it appears from the face of the instruments that extrinsic evidence is not needed to explain terms of art, or to apply the descriptions to the subject-matter, so that the court is able from mere comparison to say what is the invention described in each, and to affirm from mere comparison that the inventions are not the same, but different, then the question of identity is one of pure construction, and not of evidence, and consequently is a matter of law for the court, without any auxiliary matter of fact to be passed upon by a jury, if the action be at law.
The Court there determined that it had a case in which the question could be determined “from the mere reading of the two specifications” and that it was “too plain for argument that they are perfectly distinct.” Id., 104 U.S. at 753; see also Singer Mfg. Co. v. Cramer, 192 U.S. 265, 275, 24 S.Ct. 291, 295, 48 L.Ed. 437 (1904) (“As in each of the patents in question it is apparent from the face of the instrument that extrinsic evidence is not needed ... the question of infringement or no infringement is one of law....”); Market St. Cable Ry. Co. v. Rowley, 155 U.S. 621, 625, 15 S.Ct. 224, 226, 39 L.Ed. 284 (1894) (same as Heald v. Rice). These cases recognize that where extrinsic evidence is required and raises a real factual dispute, the question is no longer one of “pure construction,” so that the jury must play its role in the construction of the claims.
*995But where the question has arisen — where the proper construction of claims depends on the resolution of a factual dispute — the Supreme Court has stated in no uncertain terms that the jury has the duty to decide. These are cases where the meaning of a patent may not be derived from its terms alone, forcing the judge to go beyond the documentary evidence for aid. This gives rise to issues of historical fact the resolution of which must be left to a jury.
The claim before the court in Silsby v. Foote, 55 U.S. (14 How.) 218, 14 L.Ed. 391 (1852), was directed to “the combination, above described, by which the regulation of the heat of the stove, or other structure in which it may be used, is effected.” Id., 55 U.S. at 226. The specification disclosed a stove containing a number of discrete parts. To be sure, the judge “construed the claim”; he instructed the jury that it covered “a combination of such of the described parts as were combined and arranged for the purpose of producing a particular effect, viz., to regulate the heat of a stove.” Id. at 225. But the defendants asked the judge to rule as a matter of law that the parts referred to in the claim were “the index, the detaching process, and the pendulum.” Id. at 226. The trial court refused, holding that this question was for the jury.
The Supreme Court affirmed asking, “How could the Judge know this as a matter of law?” Id. Once the trial court had construed the claim and instructed the jury, “it therefore became a question for the jury, upon the evidence of experts, or an inspection by them of the machines, or upon both, what parts described did in point of fact enter into, and constitute an essential part of this combination.” Id. Only then could the jury determine if the accused device contained all of these elements and was therefore an infringement. The Court said the “defendants’ counsel exhibited to the court the models of the machines of the defendants and the plaintiff, for the purpose of satisfying the court the jury must have understood they were at liberty to construe the claim, and that they did in truth so construe it, as to exclude from the combination claimed by the plaintiff, what is called the detaching process.” Id. (emphasis added).
Again in Winans v. Denmead, 56 U.S. (15 How.) 330, 14 L.Ed. 717 (1853), the court “construed” the claim in a general manner and left it for the jury to fill in the specifics. The claim at issue was directed to a rail ear for the transportation of coal “in the form of a frustum of a cone, substantially as herein described, whereby the force exerted by the weight of the load presses equally in all directions.” Id., 56 U.S. at 342. The defendant requested the jury be instructed that the claim was limited to a circular form only, as was described in the specification and did not cover the defendant’s rectilinear design. The Supreme Court affirmed the trial court’s refusal of the instructions, stating that “where the whole substance of the invention may be copied in a different form, it is the duty of the courts and juries to look through the form for the substance of the invention— for that which entitled the inventor to his patent, and which the patent was designed to secure.” Id. at 343.
The Court considered how far an alleged infringing car could depart from the form of a perfect circle and still infringe, and determined that the claim encompassed anything “so near to a true circle as substantially to embody the patentee’s mode of operation, and thereby attain the same result as was reached by his invention.” Id. at 344. It cited evidence, including expert testimony as to the mode of operation of the patentee’s ear and whether the accused car attained the same results as the claimed ear. The Court unmistakably left it to the jury to determine the meaning of the claim, its scope, and refused to proclaim it a matter of law outside the province of the jury. Id.
These cases are especially relevant because they show that the jury has always had a role in determining a patent’s scope. This historic reliance on juries to aid the court in deciding exactly what patents protect matters here because the Seventh Amendment demands that courts preserve the right to jury trial as it existed at common law. Old cases are obviously instructive under this peculiar standard. Accordingly, efforts to distinguish Silsby and Winans because of *996their age are disingenuous. This court has no office to invoke desuetude to evade the Seventh Amendment and the Supreme Court.
Our patent laws have always required inventors to point out their inventions in detail sufficient to both distinguish the prior art and tell the public what protection the patent confers. The very first patent act required that letters patent “deserib[e] the said invention or discovery, clearly, truly, and fully.” Act of Apr. 10, 1790, ch. 7, § 1, 1 Stat. 109. The applicant for a patent was at the time required to submit “a specification in writing, containing a description ... of the thing or things by him or them invented or discovered, ... which specification shall be so particular ... as ... to distinguish the invention or discovery from other things before known and used.” Id. § 2. The word “claim” first appeared in the Act of 1836, ch. 357, § 6, 5 Stat. 117 (July 4, 1836), requiring that the applicant “shall particularly specify and point out the part, improvement, or combination, which he claims as his own invention.” Claims, per se, were not expressly required until the Act of 1870, ch. 230, § 26, 16 Stat. 198 (July 8, 1870), which said the applicant “shall particularly point out and distinctly claim the part, improvement, or combination which he claims as his invention or discovery”, but they were in common use much earlier in rudimentary form. See, e.g., Evans v. Eaton, 20 U.S. (7 Wheat.) 356, 428, 5 L.Ed. 472 (1822) (Specification concluded: “I claim as my invention, the peculiar properties or principles which this machine possesses, in spreading, turning and gathering the meal, at one operation, and the rising and lowering its arms, by its motion, to accommodate itself to any quantity of meal it has to operate on.”).
In light of this history, it is apparent that the 1870 Act simply codified the preference for particular claiming already expressed by the Supreme Court. See Brooks v. Fiske, 56 U.S. (15 How.) 212, 215, 14 L.Ed. 665 (1853) (specification and drawings to be considered “only for the purpose of enabling us to eor-rectly interpret the claim”). This change from a regime of “central” claiming to one of “peripheral” claiming may seem a major step in the patent discipline, but the distinction it represents is irrelevant to the Seventh Amendment. When the trial court in Silsby construed the claim there at issue, it was performing essentially the same task of claim construction as courts perform today. When the judge then left it for the jury to clarify the ambiguity as to just what elements the claims encompassed, he recognized the existence of a jury question precisely the same as that which the court rejects today.
Even if it were correct that the 1870 Act created a new and different claiming requirement out of whole cloth, I see no evidence that Congress thereby intended to strip the jury of its traditional role in determining patent scope. Indeed, the Seventh Amendment’s command that we preserve jury trial rights as they existed at common law dictates that Congress could not have taken the question from the jury even if it wanted to. See Granfinanciera, 492 U.S. at 51, 109 S.Ct. at 2795 (Congress “lacks the power to strip parties contesting matters of private right of their constitutional right to a trial by jury”; private rights involve “the liability of one individual to another under the law as defined” (quoting Crowell v. Benson, 285 U.S. 22, 50, 52 S.Ct. 285, 292, 76 L.Ed. 598 (1932))).
Cases involving patent interpretation in the validity context reach the same result.7 For example, in Bischoff v. Wethered, 76 U.S. (9 Wall.) 812, 19 L.Ed. 829 (1869), the Court explained that although it was normally the “province of the court, and not the jury, to construe the meaning of documentary evidence,” the “specifications of patents for inventions are documents of a peculiar kind.” Id., 76 U.S. at 815. The Court stated further that inventions, the subjects of patents, “have their existence in pais, outside of the documents themselves; and which are commonly described by terms of art or mystery to which they respectively belong; and these *997descriptions and terms of art often require peculiar knowledge and education to understand them aright.” Id. Accordingly, an understanding of the patented invention “is to be properly sought, like the explanation of all latent ambiguities arising from the description of external things, by evidence in pais,” outside of the patent document. Id. This inquiry “belong[s] to the province of evidence, and not that of construction,” and thus falls to the jury. Id. at 816.
This illustrates how claim construction may sometimes require the resolution of factual matters before a claim can be authoritatively construed. The exercise is further informed by decisions interpreting analogous instruments, for patents are legal documents like contracts or deeds. See Goodyear Dental Vulcanite Co. v. Davis, 102 U.S. 222, 227, 26 L.Ed. 149 (1880) (patent as contract); Motion Picture Patents Co. v. Universal Film Mfg. Co., 243 U.S. 502, 510, 37 S.Ct. 416, 418, 61 L.Ed. 871 (1917) (patent as deed). The analogies are most apt. A patent can be conceived of as a contract between the inventor and the government. In return for full disclosure of the invention the government gives a monopoly of sorts for a time. The rest of us may be third party beneficiaries of this deal, partaking of the advancement of knowledge the patent represents. Or a patent may be thought of as a form of deed which sets out the metes and bounds of the property the inventor owns for the term and puts the world on notice to avoid trespass or to enable one to purchase all or part of the property right it represents. The public holds a vested future interest in the property. Accordingly, patents should be interpreted under the same rules as govern interpretation of kindred documents. Merrill v. Yeomans, 94 U.S. 568, 571, 24 L.Ed. 235 (1877).
The interpretation of a contract or a deed, like a patent, is ultimately a question of law. There is nothing novel about the principle that, in the words of Justice Story, “the interpretation of written documents properly belongs to the Court, and not to the jury.” William & James Brown & Co. v. McGran, 39 U.S. (14 Pet.) 479, 493, 10 L.Ed. 550 (1840). This principle has been routinely evoked in the context of contract law. See Levy v. Gadsby, 7 U.S. (3 Cranch) 180,186, 2 L.Ed. 404 (1805) (“the construction of a written evidence is exclusively with the court”); Goddard v. Foster, 84 U.S. (17 Wall.) 123, 142, 21 L.Ed. 589 (1872) (“[I]t is well-settled law that written instruments are always to be construed by the court_”); see also Meredith v. Picket, 22 U.S. (9 Wheat.) 573, 575, 6 L.Ed. 163 (1824) (interpreting a deed, “[t]he Judges must construe the words of an entry, or any other title paper, according to their own opinion of the words as they are found in the instrument itself’).
In light of such emphatic Supreme Court language, one might conclude that the meaning of a contract is first and last a question of law which in no instance should be resolved by a factfinder. But as Justice Story also was careful to point out in McGran, “there certainly are cases, in which, from the different senses of the words used, or their obscure and indeterminate reference to unexplained circumstances, the true interpretation of the language may be left to the consideration of the jury for the purpose of carrying into effect the real intention of the parties.” 39 U.S. (14 Pet.) at 493.
Story used the facts of McGran to illustrate the point. One issue was the meaning of certain words used by the parties in letters which formed an agreement on the sale of cotton. The language was susceptible of more than one interpretation and its meaning would depend on the surrounding circumstances. Therefore, the trial judge properly refused to tell the jury what the letters meant, because to do so would have removed from the jury “matters of fact in controversy before the jury upon which it was exclusively their province to decide.” Id.
Goddard v. Foster similarly held that written instruments are for the court “except when they contain technical words, or terms of art, or when the instrument is introduced in evidence collaterally, and where its effect depends not merely on the construction and meaning of the instrument, but upon extrinsic facts and circumstances, in which case the inference to be drawn from it must be left to the jury.” 84 U.S. (17 Wall.) at 142. See also Reed v. Proprietors of Locks & Canals *998on Merrimac River, 49 U.S. (8 How.) 274, 289, 12 L.Ed. 1077 (1850) (allowing jury to interpret vague or ambiguous deed, where “it necessarily becomes a fact for the jury to decide, whether the land in controversy is included therein”).
The principle that documentary interpretation is a matter of law has become a basic tenet of modern contract law. Equally established, however, is the caveat that extrinsic evidence, such as custom and usage of the trade and course of dealing between the parties, akin to prior art, level of skill in the art, and events in the Patent Office, may be introduced to inform the meaning of terms in the contract. And when such evidence is brought in and creates a real conflict, it results in a question of fact for the jury. Great N. Ry. Co. v. Merchants Elevator Co., 259 U.S. 285, 292, 42 S.Ct. 477, 479, 66 L.Ed. 943 (1922); cf. Reed, 49 U.S. (8 How.) at 290 (meaning of deed). This is true even though in some circumstances the factual exercise of assigning meaning, to a term of a contract serves to decide the meaning of the contract. Until today, the same rule has applied in the interpretation of patents.8
. While the ultimate question of patent validity is one of law, Graham v. John Deere Co., 383 U.S. 1, 17, 86 S.Ct. 684, 693, 15 L.Ed.2d 545 (1966), there are a number of underlying inquiries that raise questions of fact. In addition to obviousness, these include anticipation, Atlas Powder Co. v. E.I. DuPont de Nemours & Co., 750 F.2d 1569, 1573, 224 USPQ 409, 411 (Fed.Cir.1985), prior public use or sale, U.S. Envtl. Prods., Inc. v. Westall, 911 F.2d 713, 715, 15 USPQ2d 1898, 1900 (Fed.Cir.1990) (a legal conclusion supported by underlying facts), and sufficiency of a specification’s disclosure, Utter v. Hiraga, 845 F.2d 993, 998, 6 USPQ2d 1709, 1714 (Fed.Cir.1988) (same).
. The court pretends there is a line of contrary authority. Ante at 986-87. But most of its cases arrived at this court after bench trials — a puzzling source for guidance on the commands of the Seventh Amendment; others actually implicating the right to a jury trial sprang from facts simply inadequate to support a reasonable jury verdict. Indeed, the one case that pays lip service to this novel rule, Read Corp. v. Portec, Inc., 970 F.2d 816, 822-23, 23 USPQ2d 1426, 1432-33 (Fed.Cir. 1992), like this case, did not require excursion beyond the patent documents themselves. There may be a reason why the court is hellbent for its result, but it does not emanate from the cases.
. Of course, the inventor's testimony as to what he intended or how he understands the patent, as opposed to his testimony as an expert, may be relevant, but is entitled to little weight in the face of evidence to the contrary. See North American Vaccine v. American Cyanamid Co., 7 F.3d 1571, 1577, 28 USPQ2d 1333, 1337 (Fed.Cir.1993) (inventor's "after-the-fact testimony is of little weight compared to the clear import of the patent disclosure itself”); Intellical, Inc. v. Phonometrics, Inc., 952 F.2d 1384, 1387, 21 USPQ2d 1383, 1386 (Fed.Cir.1992) ("where a disputed term would be understood to have its ordinary, meaning by one of skill in the art from the patent and its history, extrinsic evidence that the inventor may have subjectively intended a different meaning does not preclude summary judgment.”).
. A fact dispute cannot arise solely from testimony of a patent law expert. While this sort of testimony is acceptable, even if often overdone, as an interpretive aid to the court, it is not evidence and cannot create a genuine fact question for the juiy. See Nutrition 21 v. United States, 930 F.2d 862, 871 n. 2, 18 USPQ2d 1347, 1350 n. 2 (Fed.Cir.1991) (patent law expert's "opinion on the ultimate legal conclusion is neither required nor indeed ‘evidence’ at all”); see also Avia Group Int’l, Inc. v. L.A. Gear Cal., Inc., 853 F.2d 1557, 1564, 7 USPQ2d 1548, 1554 (Fed.Cir.1988) (conflicting opinions of legal experts create no material issue of fact).
.Of course, not every disagreement gives rise to a genuine fact question. Johnston v. IVAC Corp., 885 F.2d 1574, 1580, 12 USPQ2d 1382, 1386 (Fed.Cir.1989); see also Senmed Inc. v. Richard-Alien Medical Indus., 888 F.2d 815, 819 n. 8, 12 USPQ2d 1508, 1512 n. 8 (1989) (inventor's testimony as to meaning of "on” contrary to ordinary meaning raised no real "dispute”).
. In' one case where it appeared the Court “avail[ed] itself of the light furnished by the evidence to enable it to understand the terms used in the patent and the devices and operations described or alluded to therein,” Webster Loom Co. v. Higgins, 105 U.S. 580, 586, 26 L.Ed. 1177 (1881), the evidence was examined in ruling on the issue of enablement, i.e., whether those of skill in the art would understand the terms of the patent. Even given the conflicting testimony, the Court concluded that the terms of the patent were "sufficiently clear and full in the description of the invention.” Id. 105 U.S. at 589. When it reached the question of infringement, however, it did not mention any evidence other than the specification and claims and stated "if we examine the language of the claim [in light of the specification], it seems to us that all doubt as to its meaning is removed.” Id. at 598. There was no reliance on any extrinsic evidence in construing the claims for purposes of infringement.
. Cases about patent validity are authoritative on the issue of claim construction. A claim must be interpreted the same for both validity and infringement. E.g., Smithkline Diagnostics Inc. v. Helena Lab. Corp., 859 F.2d 878, 882, 8 USPQ2d 1468, 1471 (Fed.Cir.1988). A claim must be construed before determining its validity just as it is first construed before deciding infringement.
. After emphasizing that patents are construed according to the same rules that apply to other legal instruments, the court decides that a patent is like a contract or a deed in the context of disputes over its creation or its validity, but that when it comes to the question of infringement, a patent is like a statute. Wholly aside from the metaphysical implications of this curious duality to the traditional rule that patents are interpreted for validity just as they are for infringement, it is simply a bogus analogy.
Patents cannot be baby statutes because they are prepared ex parte by interested parties, drafted in the lower reaches of an executive department, and issued ministerially by a political officer. They have none of the indicia of a real statute, but the court imbues them with a transconstitutional power to compromise the role of juries in the third branch of government. Not even a congressionally passed, presidentially signed law can match that. See Granfinanciera S.A. v. Nordberg, 492 U.S. 33, 51, 109 S.Ct. 2782, 2795, 106 L.Ed.2d 26 (1989).