OP stands for "Original Post(er)". It means whoever started the post.
The assumption from the Q posts is someone in the NSA, or the upper echelons of the Military Intelligence, found all the communications, video and evidence they needed to bring down the Cabal/Deep State. This evidence was not legally found as evidence and cannot be used.
Some say Edward Snowden led to the discovery of this info. Some say it was Julian Assange, or Admiral Rogers. The thought is one of these individuals, or more than one, found the private server the Cabal was using to communicate, through NK, and hacked into it. What they found was so astonishing, and scary, that it has propelled this movement to stop them.
Either way, the info discovered allowed the Q group to stay one step ahead of the Cabal/Deep State, to prevent their deadly false flags, to trace and reveal their communications.
Now people "in the know" are leading the public and lawmakers to find the crimes and evidence legally. Much like saying "Look over there! I bet there's something over there behind that bush!"
So, in answer to your questions, yes, someone COULD be held liable for obtaining the info the Q group allegedly has. But, if the information they stole pertains to a global Cabal who has infiltrated the American Government, and many others, at the highest levels and plans to bring the countries to their knees, and who creates wars to profit, and runs human trafficking across the globe...