If you were an appellate judge, I imagine that you would prefer to review a lot of matters as “issues of law.” The great thing about issues of law is that issues of law make the appellate court the final arbiter of a determination. As you know, issues of law are reviewed de novo. Issues of fact are reviewed with some level of deference to the factfinder.
In the previous post, I explained that there are several issues percolating at the Federal Circuit with respect to §101 that have not yet been resolved as issues of law or issues of fact. Perhaps the prospect of giving up de novo review has something to do with that delay.
Retired Chief Judge Rader was a staunch critic of the doctrine of claim vitiation. He explained that the tests for vitiation and equivalents are coterminous. The only difference was that the doctrine of claim vitiation was an issue of law (reviewed de novo) while the doctrine of equivalents was an issue of fact (not reviewed de novo). Therefore, one could assert the doctrine of claim vitiation for purposes of summary judgment, since there could be no fact issue to dispute. You can hear him explain this in the 2007 oral argument of Wleklinski v. Targus: [Listen]. See also his “Additional views” in the Nystrom v. Trex case.
While Judge Rader does not mention it, the adoption of de novo review for the doctrine of claim vitiation also made the appellate judges the final arbiters of a doctrine of claim vitiation analysis. They do not need to defer to any factfinder.
We will have to wait and see how the Federal Circuit resolves the §101 issues.