A lot of people have emailed asking why Mick Foley is legally allowed to use the name "Cactus Jack" in TNA Wrestling.
It breaks down like this. WWE has a trademark on the name Cactus Jack but because Foley used the name prior to WWE, dating back to Independant promotions, he can continue to use it today.
The reason this doesn’t work for The Dudley Boys, for example, is because their named originated in ECW and was given to them by Paul Heyman. This means when WWE bought out ECW and their trademarks, video library, etc., they retained the ownership of the name "Dudley Boys".
While that seems clean-cut, some may remember The Dudleys were going to sue to get their name back, as Heyman allegedly signed over the rights to the name to them, but going to court to fight the battle against a company like WWE would have cost them more than it’s worth, considering they’re the same team anyways and "3-D" is an established brand along with The Dudleys, so the switch to Team 3D seemed a better fit.