As a potentially interesting point, about a dozen years ago I had to go through a corporate harassment training class (in Colorado, USA). The "instructor" was a corporate lawyer who supposedly specialized in harassment, though it seemed she probably just got licensed. Anyway, after about 90 minutes of "training" us, the audience started asking pointed questions. By the end of the 2 hour class, she agreed that their was no definitive legal definition of harassment, and that in the end it would depend upon what the the two sides in the case could convince the jury of. And that emotion was key to convincing the jury.
Maybe their is now a better legal definition, but I doubt it.
I had a friend who was a paralegal once (I think he may have gone full law school since) and he used to say that about almost all crimes and civil case.
then again he also use to joke about it being about research too, and that there was precedent for any and every thing on both sides of any argument, you just had to find themdefinitive legal definition of XXXXXXX, and that in the end it would depend upon what the the two sides in the case could convince the jury of. And that emotion was key to convincing the jury.