However, criminal is probably subject to considerable debate. Given how open the cops were (relatively speaking) about what they were doing, I'm sure there are plenty of bits of paper declaring this kosher.
And I do note that they spread the activities out over enough jurisdictions that the "test subjects" are safe from prosecution. Which does speak favourably to their claim that this is (primarily at least) about educating officers.
The reasoning behind the program even makes a certain amount of sense. (For a given value of sense and lack thereof on the part of the cops.) Cops do need to know how to recognise the outward symptoms of inebriation BEFORE they rise to the level of hospitalisation or "Some crazy, drug fucked nutter going balistic."
Even the choice of location for pickup and dropoff is going to be dictated by where peoples are at. Much the same reason Occupy chose to occuply that place.
HOWEVER, using subjects as informats THAT definitely crosses lines, but even so, it's not exactly a surprise is it?
All told though, this is probably not a worthwhile path to pursue police misbehaviour down. Best case, it might be possible to shut the program down, but no one's going to get into any great trouble over it, unless you can produce an overdose or two dumped in a skip.
It's not that this is right. It's just that it's insufficiently wrong, and seems to make just enough sense, in the eyes of those who run the show (and the public in general), for kicking up a stink to have any useful impact on the more important question of harmful police misbehaviour in general. It just devalues legitimate complaints when they occur and it's not until something as egregious as a cop CASUALLY STROLLING down a line of students with his can of milspec mace that anyone pays attention.