It will be based on two things. One is the idea that the agency, the FCC, doesn't have the authority to pass the law this way. The second is that their changing of the rule that was successful, without giving reasons for doing so, is arbitrary and capricious.
The rule in American administrative law is that you can't simply change long-standing administrative rules for purely political reasons. You have to have a change in circumstances; something has to have happened in order for you to change the rule that the industry was relying upon. The argument in court is that there was no change in circumstance; it was—