Docu-noir. The true crime documentary by which all others will forever be measured.
Remove the well-known real world effect the movie had on the case it documents (which honestly elevates it to something far more significant than just a movie). Ignore all the ways it pokes holes and exposes flaws in our justice system. And what you're left with is still a compulsively watchable, endlessly compelling piece of cinema for its formal qualities alone.
The many reenactments of the same incident give the film a Rashomon-like structure, encouraging the viewer to scrutinize every detail. Yet Phillip Glass's score combines with the smooth editing and noir-inspired imagery to send this viewer into a sort of reverie. Somehow, these seemingly contradictory qualities blend together perfectly. It's like being completely relaxed yet hyper-attuned to every detail.