As an aside, how do you lace a drink with THC? THC is the active ingredient in pot. You can’t just squeeze the pot really hard and the THC juice runs out of it (I know - I tried). It is a chemical process and the resulting product is very expensive.
I doubt he just put a pot bud in the drink, and even if he did that would not release THC into the policeman’s drink.
Thus I posit that he had a form of concentrated cannabis extract.
Most likely synthetic THC or MDPV.