Testing in court is not the way to enforce legality for police departments. Having someone let go from a crime years after they are arrested based on court proceedings would 1) be too far removed from the illegal behaviour to change that behavior, 2) not catch most illegal behaviour because, as the most likely response would be for the police department to lie about it, 3) not catch behaviour that is illegal but never makes it to court. I would much rather have police departments have strong training about appropriate evidence collection, third party oversight over police behaviour, and technical monitors of behavior such as body cams.

Edit: I just want to point out there should be court cases about it, but they should be focused on repercussions for the offending officers instead. With a model where illegal police behaviour is punished by releasing a defendant doesn't actually punish the police and forces the non-police individual pay for illegal police behaviour by being put on trial.