BerkleeX: BCM-MB110x Introduction to the Music Business - goes into great detail on the in's and out's of proving copyright infringement (taught by John P. Kellogg, Esq - you might be able to access the archived course)
Basically you need to satisfy three requirements 1. actually have a copyright (easy if you filed correctly), 2. prior access to the work (harder to prove), and 3. substantial similarity (one for the musicologists and then the jury).
most copyright infringement claims are settled out of court (e.g. "I Want a New Drug" vs "Ghostbusters"). A big factor in so many settlements is that you can be ordered to pay court costs if you lose and that juries are never a sure thing (but that is just my opinion)
I don't have an opinion on this specific case - but I will defend the concept of the copyright as crucial to the "creative" industry
in the "duck and run" category this case has my attention