concurring.
While I join the opinion of the court without reservation, I think it important to note that our adoption of the rule that claim construction is an issue of law does not mean that we intend to disregard the work done by district courts in claim construction or that we will give no weight to a district court’s conclusion as to claim construction, no matter how the court may have reached that conclusion. Simply because a particular issue is denominated a question of law does not mean that the reviewing court will attach no weight to the conclusion reached by the tribunal it reviews. In fact, reviewing courts often acknowledge that as to particular legal issues lower tribunals have special competence and their judgments on those legal issues should be accorded significant weight. For example, the Supreme Court typically defers to the construction of a state statute adopted by the regional court of appeals that includes that state. See Propper v. Clark, 337 U.S. 472, 486-87, 69 S.Ct. 1333, 1341-42, 93 L.Ed. 1480 (1949). Similarly, this court has routinely noted that although contract interpretation is a question of law, the interpretation of a contract by a Board of Contract Appeals, in light of the Board’s expertise in such matters, “is afforded careful consideration and great respect.” Alvin, Ltd. v. United States Postal Serv., 816 F.2d-1562 (Fed.Cir.1987): Indeed, the Supreme Court has made much the same point in referring to its review of this court’s decisions on patent law, noting that the Court would “leave such refinement [óf the legal test for applying the doctrine of equivalents] to [the Federal Circuit’s] sound judgment in this area of its special expertise.” Warner-Jenkinson Co. v. Hilton Davis Chem. Co., — U.S. -, -, 117 S.Ct. 1040, 1054, 137 L.Ed.2d 146 (1997).
The Supreme Court in Markman stated that it would be a rare case in which claim construction would turn on an issue such as a credibility judgment between two competing expert witnesses. See 517 U.S. at 388-90, 116 S.Ct. at 1395. Such cases, however, may arise, and in those cases it would be entirely appropriate — and consistent with our characterization of claim construction as a question of law — to factor into our legal analysis the district court’s superior access to one of the pertinent tools of construction.
That does not mean that we defer to a district court on legal matters unless we find that the court has committed clear error with respect to an issue that should be characterized as factual. What it means is that we approach the legal issue of claim construction recognizing that with respect to certain aspects of the task, the district court may be better situated than we are, and that as to those aspects we should be cautious about substituting our judgment for that of the district court.