I'm seeing a lot of comments in this thread about Kraft going after the NFL's antitrust exemption. Kraft doesn't need to challenge the NFL's antitrust exemption, which benefits him as much as anyone, to sue the NFL in court. Unions have an antitrust exemption and they get sued all the time. If Kraft sues the NFL it will most likely be for breach of contract. The argument would be that the NFL acted arbitrarily and capriciously in punishing the Patriots without justification and thereby violated an implied duty of good faith and fair dealing under the contract. The question would be whether Kraft has contractually waived his right to sue the league, either because it's prohibited by the NFL's constitution or by some other agreement Kraft has made with the league.