Corroborate and We Make You Wait: Patent Invalidation Requires Corroborating Evidence

In Adenta GMBH v. OrthoArm and American Orthodontics, the Court of Appeals for the Federal Circuit recently applied its long-standing "rule of reason," under which one peson's testimony alone is not enough to invalidate a patent; instead, some corroborating evidence is necessary.

This leads me to wonder whether there are any other claims that require corroborating evidence in order to be proven.  Most states used to have requirements that rape allegations needed corroborating evidence in addition to the alleged victim's testimony, but those requirements have been taken off the books.  I'm not aware, though, of any similar rules that still exist categorically to preclude the success of certain types of claims.  Is this "rule of reason" thus unique?  I know that corroboration is required to admit certain evidence, such as statements against interest under Fed. R. Evid. 804(b)(3), but that seems like a different animal entirely.

-CM