a. Subject to subsection b. of this section, it is an affirmative defense that the actor engaged in the conduct charged to constitute an offense because he was coerced to do so by the use of, or a threat to use, unlawful force against his person or the person of another, which a person of reasonable firmness in his situation would have been unable to resist.
b. The defense provided by this section is unavailable if the actor recklessly placed himself in a situation in which it was probable that he would be subjected to duress. The defense is also unavailable if he was criminally negligent in placing himself in such a situation, whenever criminal negligence suffices to establish culpability for the offense charged. In a prosecution for murder, the defense is only available to reduce the degree of the crime to manslaughter.
c. It is not a defense that a woman acted on the command of her husband, unless she acted under such coercion as would establish a defense under this section. The presumption that a woman, acting in the presence of her husband, is coerced is abolished.