“The law as it was understood... by whom?”
Everyone. It was not until AFTER the stop that a lower court ruled a car only needed one taillight, and the NC Supreme Court indicated they might not endorse that view had they been asked.
At the time of the stop, it was completely reasonable to believe the law required full working lights. As the NC Supreme Court noted, it might well be true.
However, the search was not based on the lights. It was based on the cop’s suspicions after talking to the parties, and on the owner of the car agreeing to the search.
That doesn’t mean “everyone.” That meant at WORST it was open for debate.
Courts greased the skids for the jackboots here. No doubt about it.
Anyhow, what was the controlling court in the jurisdiction in which this happen. If it was the one that declared only one light was needed, then the higher court had a chance to nix that and failed. Therefore the lower court’s definition of the meaning of the law should prevail and all else follow by consequences.
If we are not under a rule of law we are under a rule of men.