If one has committed illegal act A or B, but we cannot prove that A was committed or B was committed, is one generally proven guilty of a crime?
<p>Imagine a scenario where you know beyond a reasonable doubt that somebody did something wrong, but you couldn't prove exactly what it was.  It could have been A or B.  But you cannot prove it was A and you cannot prove it was B.</p>

<p>EDITED TO ADD A SCENARIO:</p>

<p>Imagine a marijuana salesman is being charged with fraud.  His accuser states that he has been sold fake marijuana which constitutes fraud.  The selling of marijuana is also considered a crime.  Multiple witnesses attest to the fact that the marijuana seller was purporting to sell marijuana.  The evidence has been smoked.  There is no way to determine whether there was a fraud or whether there was an illegal sale of marijuana.  But the number of witness reports puts it beyond a reasonable doubt that one of the two occurred.  </p>

<p>In a common law jurisdiction in the circumstances you describe you cannot be <em>charged</em> with a crime; much less proved guilty of it.</p>

<p>In <a href="http://www.austlii.edu.au/cgi-bin/sinodisp/au/cases/cth/HCA/2010/1.html?stem=0&amp;synonyms=0&amp;query=title(kirk%20)" rel="nofollow">Kirk  v Industrial Relations Commission;  Kirk  Group Holdings Pty Ltd v WorkCover Authority of New South Wales (Inspector Childs) [2010] HCA 1 (3 February 2010)</a> the High Court said:</p>

<blockquote>
  <p>The common law requires that a defendant is entitled to be told not only of the legal nature of the offence with which he or she is charged, but also of the particular act, matter or thing alleged as the foundation of the charge</p>
</blockquote>

<p>In this, they were relying on the decision in <a href="http://www.austlii.edu.au/au/cases/cth/HCA/1937/77.html" rel="nofollow">Johnson v Miller [1937] HCA 77; (1937) 59 CLR 467 (16 December 1937)</a>, however, as the style of decision writing in the early part of the twentieth century involved using page long unnumbered paragraphs, there is no appropriately pithy quote available from that case.</p>

<p>Further, your example is flawed - public policy dictates that a person defrauded in a criminal enterprise has no recourse to the law - there is no fraud here as the underlying "contract" was void for criminality. A person engaged in a joint criminal enterprise also has no duty of care to his co-criminals.</p>

<p>In most judicial systems, the judgment must name the exact crime the accused is convicted for. When the prosecution can not prove that the accused committed a <em>specific</em> crime, the suspect must be acquitted.</p>

<p>I am answering this question under the laws of the state of New Jersey.
The elements of fraud in New Jersey are:
(1) a material misrepresentation of a presently existing or past fact;
(2) knowledge or belief by the defendant of its falsity;
(3) an intention that the other person rely on it;
(4) reasonable reliance thereon by the other person; and
(5) resulting damages</p>

<p>Each element must be proven beyond a reasonable doubt. Since they do not have a sample of the substance. They cannot prove these elements. There is no way to prove 1 or 2.</p>

<p>Now let's look at distribution:
The elements are: (simplified)
1. The substance is (insert appropriate CDS or controlled substance analog).
2. The defendant possessed, or had under (his/her) control, substance.
3. The defendant, when (he/she) possessed or had under (his/her) control substance had the intent to distribute S in evidence.
4. That the defendant acted knowingly or purposefully in possessing or having under (his/her) control with intent to distribute Substance in evidence.</p>

<p>There is no way to prove element 1, that the substance sold was in fact an illegal drug.</p>

<p>There is reasonable doubt to both counts the defendant could be charged with.
The jury must acquit, judge should dismiss or at least sever the case to not prejudice the defendant's due process rights.</p>

<p>Sources:
<a href="http://www.davidrichlaw.com/what-are-the-elements-of-fraud-in-new-jersey/" rel="nofollow">http://www.davidrichlaw.com/what-are-the-elements-of-fraud-in-new-jersey/</a>
<a href="http://www.njlaws.com/possession_with_intent_to_distribute.htm" rel="nofollow">http://www.njlaws.com/possession_with_intent_to_distribute.htm</a></p>

due-process