MetLife decided to review the case and, well, they didn't do a very good job of it. The doctors they had evaluate the plaintiff didn't really use any evidence and when they did, they did so selectively.
There is no one test that can be used for CFS because it is an amalgam of several symptoms rather than a disease. So all the tests that the plaintiff's primary care physician said pointed to CFS, MetLife's docs said they didn't, claiming that there was not objective proof of the condition. And when they were asked repeatedly what the plaintiff could do to provide objective proof (remember there is no test for CFS) the question was ignored.
Brilliant. The insurance companies want a level of proof that's not possible. A definitive result from a non-existent CFS test.
The opinion, linked above, is quite a good read. The judge really goes after MetLife on some of its self-contradictions and gets after a MetLife doc's report saying it "can be characterized as shoddy and incomplete."
The whole point is that insurance companies have to be responsive and specific when they deny a claim. They have to answer the question of why the claim was denied and also explain what they would need to accept it. If they don't, something's up.