Section 626:7 - Defenses; Affirmative Defenses and PresumptionsI.When evidence is admitted on a matter declared by this code to be: (a) A defense, the state must disprove such defense beyond a reasonable doubt; or(b) An affirmative defense, the defendant has the burden of establishing such defense by a preponderance of the evidence.II.When this code establishes a presumption with respect to any fact which is an element of an offense, it has the following consequences: (a) When there is evidence of the facts which give rise to the presumption, the issue of the existence of the presumed fact must be submitted to the jury, unless the court is satisfied that the evidence as a whole clearly negatives the presumed fact; and(b) When the issue of the existence of the presumed fact is submitted to the jury, the court shall charge that while the presumed fact must, on all the evidence, be proved beyond a reasonable doubt, the law declares that the jury may regard the facts giving rise to the presumption as sufficient evidence of the presumed fact. 1971, 518:1, eff. Nov. 1, 1973.