Davis' argument was that the Tweety Bird didn't obstruct his vision, so the cops had no right to pull him over, and therefore the items they found should be suppressed. The 6th Court of Appeals initially struck down the Michigan law since it does not define "to what degree the driver's vision must be obstructed or for how long." Noting that a great many cars have objects dangling from their mirrors, and so may be in unwitting violation of the law, "the statute itself provides no guidance either to motorists or police as to which ones" violate the law, and so must be scrapped.
The court didn't suppress the evidence, and shortly after its ruling it rescinded its decision striking down the ban. The reason is thought to be that the court was required to let Michigan plead its case for the ban before the court struck it down. The court has not given a reason for its reversed decision. As far as the now-reinstated fuzzy dice ban, for now it remains a reason for the police to pull you over if and when they decide.
[Source: Michigan Messenger]