I was doing due diligence on a computer security firm once who had be subject to a DDoS blackmail attack, you know, give us $5,000 or will we will keep your web site down. Well they back traced the control to some cyber cafe in eastern Europe and worked with the State Department to actually get the local police to go in and arrest the people involved.
If someone is actively hacking you then hacking them back isn't a crime (or it shouldn't be) its just self defense. And if you have to hire some firm to do it I don't see how it is any different than hiring armed security guards or private detectives.
If the law says you can't defend yourself from someone trying to ruin your business then the law is an ass.
Equal to "If someone breaks into your home, you should be able to break into their home."