I'm just giving you an account of my experience. Where the policeman lied was when he took the stand and claimed I had told him "Sorry mate I thought it was 40 down here" when I never said such a thing.
I've watched enough crime shows to know you STFU when stopped by a police officer and that's pretty much what I did.
I can't tell you how angry I was when that officer stood up and said that, mainly because before that, like you, I thought of them as upstanding members of the community trying to do a tough job honestly.
Luckily, I managed to stop myself shouting "objection your honour"
But if your position is it is OK for police officers to lie and break guidelines just so long as they get the conviction then I'll respectfully disagree with that position.