Rudy is right, collusion is not a crime. One can collude in planning a surprise birthday party. Such collusion is only a crime if the birthday party is illegal and if it actually takes place. Even then, collusion is only a compounding element.
Collusion is a loose synonym to collaboration or participation.
There is a bit of sophistry in saying collusion is not a crime. Mostly it is an attempt to re-focus on the wrong question.
— Kilgore Forelle