If you pass a marked police car on a motorcycle traveling in the opposite direction and you are speeding and the police do not give chase sound their siren or use their lights to stop you, can you be prosecuted?
How fast do you think that you were going? It all depends whether or not they captured evidence of your speed. Sometimes they can track your distance traveled and the time taken from the other side of the road. This allows them to calculate your speed.
Have you got any points already? If so, how many?