Could you imagine how dumb you have to be to see a car sitting to make a right (on to you), and you decide to go into the lane to pass?
Not as careless or dumb as to be making a right turn onto a road and not first
looking in the direction you will be going to make sure your path is clear.
The more prevalent and classic error here (not effing looking to make sure the direction you are going to go is clear) would be anot seeing a pedestrian or a kid on a bicycle entering your intended path.
Sorry, but the OP was negligent. If he was so careless as to fail to notice an oncoming police cruiser, how badly would he have felt if had slaughtered a smalller, harder to see pedestrian?
If there really is a marked passing lane, right at this spot, that shouldn't trump common sense and the desire for self-preservation.
Common sense,
legal and moral duty, and the desire for self-preservation are exactly why the OP should have dead nuts looked to see if the path he was preparing to take was clear.
There is simply no valid excuse for his not doing so.