The ruling will finish the association's nationwide limits on education-related benefits athletes can receive for playing college sports.
In upholding lower-court rulings, the justices affirmed an injunction that could fundamentally alter the NCAA's method of amateurism.
Trainers playing Division I men's or women's basketball or Bowl Subdivision soccer will be able to get benefits from their schools which include cash or cash-equivalent awards according to professors or graduation.
Among the other advantages that colleges can also provide are scholarships to complete graduate or undergraduate degrees at any school and paid internships after athletes have completed their collegiate sports qualification.
Schools won't be asked to supply these kinds of gains, and conferences can impose prohibitions on certain benefits if their member schools so choose. But, conferences can't behave in concert. So, if a seminar chooses to limit or stop certain benefits, it risks giving a competitive edge to other seminars.
The ruling appeared likely to have an indirect impact on the NCAA's attempts to operate through a variety of different issues, such as athletes' ability to make money from non-university entities off their name, image and likeness (NIL).
Kavanaugh added that the NCAA"must supply a legally valid" rationale that"its remaining compensation rules" have sufficient value to boosting competitive balance and that the benefits outweigh the harm being done to the athletes.
"As I see it, however, the NCAA may lack such a rationale," Kavanaugh wrote.
In a meeting with USA TODAY Sports, NCAA President Mark Emmert, NCAA general counsel Scott Bearby and outside attorney Jeffrey Mishkin said little weight ought to be given to what Kavanaugh wrote.
"The notable thing is that eight other justices did not agree with this and would not sign on to it," Mishkin said. "So I don't think that you can make very much of that concurrence. It is his own opinion, and he is writing for himself. So, I believe that's simply not at all fundamental to what has been decided now."