The NLRB recently ruled that football players at Northwestern University be allowed to unionize.
Back in 2004, in a case involving our own Brown University, they ruled that grad students at private universities could not.
This article summarizes their logic in reaching the different decisions.
Especially circular is the last argument, which is that TAs and RAs are not “paid for services performed”, because they make no more money than students on fellowship. Since they are not paid for their work, they cannot be considered employees, and because they cannot be considered employees, they cannot unionize, and, you know, demand pay for their work.