I would be extremely surprised if the NRL and the Dogs took any legal action beyond seeking compensation for SBW's breach of contract. Seeking an injunction would simply not be in their interests - whilst it has been some time since I practiced contracts law, it would be an extremely tricky matter to stop SBW playing Union. Moreover, even if the NRL was successful, the sheer cost of the legal battle would render such an action highly imprudent. Not only would the NRL find itself dragged into a protracted legal challenge that could drag on for months, it would protract the media attention surrounding SBW and give him more opportunities to badmouth his former club and code.
Posters here seem to be obsessed with the idea of making SBW pay for what he's done to our game, but really, making someone pay isn't good business sense unless they're paying something to you.
Spot on mate, I posted something similar in another thread. The Bulldogs and the NRL should forget about revenge and concentrate on what is best for the game and the club. That probably means getting as much compensation as possible.