Sorry, I don't have time, gotta get dressed for work. You could start by reading a text on appellate practice and procedure in the federal courts. This case has never been litigated in the federal courts. Because Congress passed a law granting the right to a trial de novo, collateral estoppel and res judicata are inapplicable. Best of luck with your legal studies.
Thanks for the answer.
I can see how they wouldn't apply in the first trip through the federal courts, but why not the second?
(Appellate practice and advanced fed procedure will come later in my legal studies.)