In a concise, 23-page opinion (PDF), the Court explained that the NFL is not a single entity because “the NFL teams do not possess either the unitary decisionmaking quality or the single aggregation of economic power characteristic of independent action.”
The court further stated that "[i]f the fact that potential competitors shared profits or losses from a venture meant the venture was immune from [Section 1 of the Sherman Act], then any cartel could avoid antitrust law simply by creating a joint venture to serve as the exclusive seller of their competing product."
I have posted a full discussion of this ruling and its implications on Above the Law, here.
As far as the case's likely outcome upon remand, I note:
[W]hether American Needle will ultimately prevail on the merits remains far from settled. As Rutgers School of Law-Camden professor Michael Carrier noted in a recent law review article, defendants have won 221 of the past 222 cases that have involved a court’s final determination under the Rule of Reason (link to Professor Carrier’s article)
In addition, even if the NFL clubs’ licensing practices have led to some anti-competitive effects, league-wide trademark licensing might also produce some pro-competitive benefits by reducing the transaction costs of obtaining licenses to use all club logos on a single piece of merchandise (link to my law review article).