Teva's Copaxone: does the CAFC have to treat an expert's opinion as a fact under FRCP 52?

Scott Gottlieb's post FDA's Looming Decision On A Generic To Teva's Copaxone Reveals Drug Approval Woes has a nice discussion of the issues facing the FDA on analyzing/approving generic Copaxone.

Gottlieb stated:


FDA is widely known to be considering the approval of a generic version of Teva Pharmaceutical’s (NYSE:TEVA) blockbuster drug for multiple sclerosis, Copaxone.
The patents covering Copaxone for its 20mg/ml strength expired on May 24th. After patent expiration, FDA could approve generic copies of the drug at any time. But some of the same challenges that caused the agency to struggle with and sometimes stumble over its similar previous decisions still linger, and will color FDA’s decision concerning Copaxone.


Meanwhile, as to the Teva v. Sandoz business on US Patent No. 5,800,808 coming before the US Supreme Court, note the following.

Scotusblog defined the issue as


In the Teva case, the issue is the division of roles between a trial court — a U.S. district court — and the U.S. Court of Appeals for the Federal Circuit over the interpretation of the claims that an inventor makes for a product or process. While federal appeals courts normally are to review the factual conclusions drawn by a district court only to see if they were “clearly erroneous,” the Federal Circuit for more than fifteen years has followed the practice of construing the claims made by an inventor, using its own independent judgment (technically, de novo review). The issue the Justices will decide is whether to require the Federal Circuit to follow the customary approach.





From within Teva's opening brief:


While the patent did not expressly use the term “peak average molecular
weight,” it did indicate that the average molecular
weight should be determined using an analytical
technique called size exclusion chromatography (“SEC”).
Dr. Grant explained that the patent’s instruction to
determine the average molecular weight using SEC
technology would have indicated to a skilled artisan
that the intended measure was peak average, the on-
ly measure that can be read directly from an SEC
chromatogram.
(...)
Peak average is the only expression of average mo-
lecular weight that can be derived directly from the
chromatogram. Determining either number average
or weight average molecular weight, by contrast, re-
quires additional calculations based on the underly-
ing chromatographic data. The patent does not spec-
ify any such further calculations.


The key point:

The district court credited Dr. Grant’s testimony
on this point, which was unrebutted, and found that
once a skilled artisan learned that “average molecu-
lar weight” would be determined using SEC, “the
presumed meaning” of “average molecular weight” to
that skilled artisan would have been peak
average.


In context, Dr. Grant was rendering an opinion as an expert
witness, not stating a fact as a fact witness. Opinions are different from facts.
An opinion is a conclusion reached by someone after looking at the facts.

I myself have a Ph.D. in physical chemistry, and can say "the use
of size exclusion chromatography" would not cause me to presume "average
molecular weight" meant "peak average molecular weight."

The experimental approach to collect data (here, size exclusion
chromatography) is distinct from "how" the data from the experiment is analyzed.