McKinnon is taking the NRL and McLean to court over a tackle that left him paralysed.
Gallen told News Corp the case could open up “a real can of worms”.
“It will be something players will be concerned about, for sure, especially if you are allowed to sue individuals,” he said.
“I still think everyone will go into a tackle as hard and fierce as ever, to be honest with you.”
Gallen said the tackle incident was “just a dreadful, dreadful accident.”