Earlier quoted context omitted.
> Is personal information really a kind of property, that can be stolen? If it is, aren’t we doing this all the time, any time we perceive anything about anyone? We are flexible and smarter than Vulcans. Something doesn't have to be necessarily expressible into a single, unambiguous universal formula to be made illegal. We can e.g. allow people to perceive things about other people in their brains (or even notebooks)…
Rule of law demands it be clear what is and is not illegal. Make it illegal to film people in public and the guy who made the Rodney King tape is going to jail.
While it would be nice, there's actually not really such a requirement. New legal theories are brought in criminal cases from time to time.
The existence of novel legal theories in criminal cases means it's not always knowable precisely what is and is not illegal.
The world is shades of grey, not black-and-white, and that's especially true in criminal law.