(1) Conduct which the actor believes to be necessary to avoid an imminent harm or evil to the actor or to another is justifiable provided that:
(a) The harm or evil sought to be avoided by such conduct is greater than that sought to be prevented by the law defining the offense charged;
(b) Neither the Code nor other law defining the offense provides exceptions or defenses dealing with the specific situation involved; and
(c) A legislative purpose to exclude the justification claimed does not otherwise plainly appear.
(2) When the actor was reckless or negligent in bringing about the situation requiring a choice of harms or evils or in appraising the necessity for the actor's conduct, the justification afforded by this section is unavailable in a prosecution for any offense for which recklessness or negligence, as the case may be, suffices to establish culpability.
(3) In a prosecution for escape under section 710-1020 or 710-1021, the defense available under this section is limited to an affirmative defense consisting of the following elements:
(a) The actor receives a threat, express or implied, of death, substantial bodily injury, or forcible sexual attack;
(b) Complaint to the proper prison authorities is either impossible under the circumstances or there exists a history of futile complaints;
(c) Under the circumstances there is no time or opportunity to resort to the courts;
(d) No force or violence is used against prison personnel or other innocent persons; and
(e) The actor promptly reports to the proper authorities when the actor has attained a position of safety from the immediate threat.