Because jury verdicts must be unanimous under Rule 31(a) of the Superior Court Rules of Criminal Procedure, and because the state bears the burden of proof in criminal cases, it is unsurprising that the prosecution refused to stipulate to the seating of more than twelve jurors on the deliberating panel. See State v. Stallman, 78 R.I. 90, 93, 79 A.2d 611, 612 (1951) (“[T]he state always has the burden of establishing [a defendant's] guilt beyond a reasonable doubt * * *.”). Furthermore, this Court has held that a criminal defendant does not possess “the right to be tried by any particular juror.”

"manifest distinction between the evidentiary concepts of the burden of production and the ultimate burden of proof. While the accused never bears the burden of satisfying the factfinder of his innocence or justification, and the prosecution always bears the burden of proving the guilt of an accused beyond a reasonable doubt in a criminal prosecution (State v. Brown, 97 R.I. 95, 196 A.2d 138 (1963); State v. Stallman, 78 R.I. 90, 79 A.2d 611 (1951)), the burden of going forward with the evidence may indeed shift from side to side, and this same burden may properly devolve upon a defendant once the state has developed a prima facie case and has adduced evidence sufficient to make it just that the defendant be required to challenge the proof with excuse or explanation. See Patterson v. New York, 432 U.S. 197, 203 n.9, 97 S.Ct. 2319, 2323 n.9, 53 L.Ed.2d 281, 287 n.9 (1977), citing Morrison v. California, 291 U.S. 82, 54 S.Ct 281, 78 L.Ed. 664 (1934).

The defendants have overlooked the manifest distinction between the evidentiary concepts of the burden of production and the ultimate burden of proof. While the accused never bears the burden of satisfying the factfinder of his innocence or justification, and the prosecution always bears the burden of proving the guilt of an accused beyond a reasonable doubt in a criminal prosecution ( State v. Brown, 97 R.I. 95, 196 A.2d 138 (1963); State v. Stallman, 78 R.I. 90, 79 A.2d 611 (1951)), the burden of going forward with the evidence may indeed shift from side to side, and this same burden may properly devolve upon a defendant once the state has developed a prima facie case and has adduced evidence sufficient to make it just that the defendant be required to challenge the proof with excuse or explanation. See Patterson v. New York, 432 U.S. 197, 203 n. 9, 97 S.Ct. 2319, 2323 n. 9, 53 L.Ed.2d 281, 287 n. 9 (1977), citing Morrison v. California, 291 U.S. 82, 54 S.Ct. 281, 78 L.Ed. 664 (1934).

It is well settled, however, that in a criminal case the burden of the state extends no further than to prove beyond a reasonable doubt only the essential constituent elements of the offense charged. State v. Deans, 93 R.I. 266, 174 A.2d 666 (1961); State v. Stallman, 78 R.I. 90, 79 A.2d 611 (1951). The statutory exceptions obviously do not establish elements of the offense of driving to the left of center, and the burden of proving that one of them comes within such an exception is, as an affirmative defense, on the defendant.

See, Chaffee Co. v. United States, 85 U.S. (18 Wall.) 516, 21 L. ed. 908; James v. State, 167 Ala. 14, 52 So. 840; State v. Bailey, 79 Conn. 589, 65 A. 951; People v. Tubbs, 147 Mich. 1, 110 N.W. 132. In State v. Stallman, 78 R.I. 90, 93, 79 A.2d 611, 612, the court said: "* * * While a defendant never has the burden of proving his innocence, and on the whole case the state always has the burden of establishing his guilt beyond a reasonable doubt, nevertheless after the state has made out a prima facie case the burden of adducing evidence to support an affirmative defense devolves upon him. Especially is this true when as a justification or excuse a defendant is relying on a fact the subject matter whereof lies peculiarly within his knowledge and relates to him personally."

To place this burden upon the state in any circumstance would do violence to the well-settled rule that in criminal cases the burden of the state extends no further than to prove beyond a reasonable doubt only the essential constituent elements of the offense charged. In State v. Stallman, 78 R.I. 90, this court held that a defendant who sought to prove that he came within the terms of an exception set out in a statute defining a crime was raising a defense which was in the nature of an affirmative defense. We are unable to perceive any sound reason for not taking the same view of evidence offered to establish the existence of some fact which, from its nature, would tend to establish the nonexistence of a constituent element of the crime with which the defendant is charged.