The reason is given in Powell v. Texas, 392 U.S. 514, 533 (1968): ...criminal penalties may be inflicted only if the accused has committed some act, has engaged in some behavior, which society has an interest in preventing.The burden of proof is on the prosecution to prove each "element of the offense" in order for a defendant to be found guilty.
The Model Penal Code §1.13(9) offers the following definition of the phrase "elements of an offense": (i) such conduct or (ii) such attendant circumstances or (iii) such a result of conduct as In United States v. Apfelbaum, 445 U.S. 115, 131 (1980),[1] Justice Rehnquist states, in his opinion for the Court, the general rule that: For these purposes, the term "actus reus" does not have a single definition, but it represents the general principle that before an individual may be convicted of an offense, it must be shown that there was an overt act in pursuance of any intention.
Thus, as the MPC §1.13(9) definition indicates, the attendant circumstances will be the evidence that must be adduced to prove all the elements required to constitute the offense and, under §1.13(9)(c) to disprove any excuse or justification.
So, as in State of North Carolina v Vernon Jay Raley 155 NC App 222 (01-1004),[2] if a citizen intentionally utters a profanity at the police, the charges would be preferred under N.C.G.S.
§14-288.1(8) as follows: In order for a person to be found guilty of this crime, the evidence must prove that the defendant uttered a profanity (the act) in a public place (the contextual attendant circumstance) with the intention of provoking a violent reaction (the mental element demonstrating the right type of culpability) and thereby causes a breach of the peace (the result prohibited by law).
The elements of a crime may also require proof of attendant circumstances that bring the conduct within time for the purposes of any statute of limitation or before an appropriate venue.