I found the original source photo that a few where discussing in another thread. Looks like Pac is standing..
and.. I don't know.. In the original thread somme other forum members we're arguing over whether he was standing or sitting and if the cop was actually that much taller than Pac.
Let's see, Adam is listed as 5'10" assuming that's right, the cop could probably be about 6'3" or 6'4" (about half a foot taller) and the height difference could look about like that depending on the camera angle, yeah, that's believeable.