If a guy 21 years old has "conscentual sex" with a girl who lied about her age stating she was 18, when she was really 15, and the guy honestly believed she was old enough, can the guy use the "criminality of conduct" as a defense, or is he guilty? And was are the consequences for said act?

Criminality of Conduct is an accepted defense where the charges are filed based soley on the age of the victim; where the victim lied to the actor and the actor had a reasonable belief that the age of the victim was older than 16.

Things that can help establish this defense or a "reasonable belief" would be, if he met her in an establishment where alcohol was served and it was reasonable to assume that all who dwell within the establishment are of legal age to drink; or, if she worked at an establishment known only to hire people 18 years of age or older; any evidence or scenario that is compelling enough to prove that a reasonable person would have believed the same, can be used as a defense. If the 21 year old has been charged with a crime in this situation, we would strongly encourage he seek advice of Wyoming attorney prior to using this defense and prior to any court appearances.

6-2-308. Criminality of conduct; victim's age

(a) Except as provided by subsection (b) of this section, if criminality of conduct in this article depends on a victim being under sixteen (16) years of age, it is an affirmative defense that the actor reasonably believed that the victim was sixteen (16) years of age or older.

(b) If criminality of conduct in this article depends upon a victim being under twelve (12) years or under fourteen (14) years, it is no defense that the actor did not know the victim's age, or that he reasonably believed that the victim was twelve (12) years or fourteen (14) years of age or older, as applicable.

Without knowing what the charge is, if any, it would be is difficult to say exactly what the consequence might be. There is a range of violations that this might fall under depending on the circumstances and a range of punishments from 1 year all the way up to 20 years in prison.