(a) General rule.--Except as provided in subsection (b) of this section, it is immaterial to the liability of a person who solicits or conspires with another to commit a crime that:
(1) he or the person whom he solicits or with whom he conspires does not occupy a particular position or have a particular characteristic which is an element of such crime, if he believes that one of them does; or
(2) the person whom he solicits or with whom he conspires is irresponsible or has an immunity to prosecution or conviction for the commission of the crime.
(b) Exception.--It is a defense to a charge of solicitation or conspiracy to commit a crime that if the criminal object were achieved, the actor would not be guilty of a crime under the law defining the offense or as an accomplice under section 306(e) of this title (relating to status of actor) or section 306(f)(1) or (2) of this title (relating to exceptions).