I did check myself before I posted that. In fact, if you type “intent is 9/10 of the law” into DDG, the entire first page of results gives you “possession is 9/10 of the law” instead.
But to be fair, I did see two examples of the intent version after scrolling through the first few pages.
That's literally the basis of qualified immunity. If law enforcement gets a pass explicitly due to ignorance of the law, why wouldn't their financiers? Further, if the punishment for the crime is a fine, then the law can only ever meaningfully punish the poor. The concept of law is working exactly as intended in this country.
Qualified immunity protects the police (or other state actors) from civil suits arising from their conduct while lawfully performing their duties. It does not shield them from criminal prosecution.
The civil suits that only have standing when there is criminal conduct already involved? You don't get one without the other. The only practical difference to a member of the public is the legal standard needed to prove guilt. Seeing as the criminal justice deck is already stacked in the favor of protecting their own enforcer, the difference is moot. It remains one of the only legally viable defenses where ignorance of the law is an acceptable excuse.