In the United States who has the authority and what is the procedure to determine if conduct by an individual is &quot;illegal&quot;?
<p>This is a canonical question posed for the purpose of clarifying the rules of criminal procedure in the United States relevant to who is authorized by law to determine if alleged conduct is "illegal". </p>

<p>In an climate of local and national political scandal and intrigue being reported in popular media questions might arise by persons who follow politics asking if general or specific conduct by individuals is "illegal", according to the language or notion of the spirit of particular laws; for example, see <a href="https://politics.stackexchange.com/questions/32748/was-attending-the-meeting-by-trump-jr-kushner-or-manafort-an-act-to-effect-t/">Was attending the meeting by Trump Jr., Kushner or Manafort, an “act to effect the object of the conspiracy” within the meaning of 18 U.S.C. 371?</a>; <a href="https://politics.stackexchange.com/q/32934/21216">Is paying for ex-staff's silence a legal use of campaign funds?</a> (see also <a href="https://politics.meta.stackexchange.com/q/3562/21216">What is the reason for deleting this users' answer at “Is paying for ex-staff's silence a legal use of campaign funds?”</a>).</p>

<p>It is important to at least attempt to reign in wild speculation as to whether an individuals' conduct is "illegal" by reiterating the facts of constitutional rights and criminal procedure within the United States.</p>

<hr>

<p>In the United States who has the authority and what is the procedure to determine if conduct by an individual is "illegal"?</p>

<blockquote>
  <p>In the United States who has the authority and what is the procedure to determine if conduct by an individual is "illegal"?</p>
</blockquote>

<p>You are conflating several different ideas here, which is probably the source of your persistent confusion.  </p>

<h2>1) Actions are legal or not</h2>

<blockquote>
  <p><a href="https://thelawdictionary.org/illegal/" rel="noreferrer">Illegal:</a> Not authorized by law; Illicit ; unlawful; contrary to law</p>
</blockquote>

<p>The law sets out certain things that you must do (you <a href="http://www.leg.state.fl.us/Statutes/index.cfm?App_mode=Display_Statute&amp;Search_String=&amp;URL=0300-0399/0316/Sections/0316.075.html" rel="noreferrer">must stop at a red light</a>) and things you must not do (you <a href="http://www.leg.state.fl.us/Statutes/index.cfm?App_mode=Display_Statute&amp;Search_String=&amp;URL=0300-0399/0316/Sections/0316.193.html" rel="noreferrer">must not drive under the influence</a>).  Sometimes actions fall into a gray area of the law, or aren't addressed at all, but <em>if</em> something is spelled out, then it's very clear whether <strong>the abstract action</strong> is legal or not.  </p>

<p>Running a red light is illegal.  Driving under the influence is illegal.  There are definitions and specified penalties for both.</p>

<h2>2) A person may or may not be guilty of an illegal action</h2>

<blockquote>
  <p><a href="https://thelawdictionary.org/guilty/" rel="noreferrer">Guilty:</a> Having committed a crime or tort</p>
</blockquote>

<p>Abstract actions can be legal or illegal, but people commit crimes.  When someone commits a crime, they are <strong>guilty</strong> of that crime.  This is true whether or not they are ever prosecuted, or even if law enforcement knows who the guilty one is.  If someone runs a red light at 2 in the morning on an empty street, it's still illegal and thus they are guilty of running a red - but no one will ever catch them.  If someone is shot in the middle of the street, then <em>someone</em> is guilty of shooting them. Again, the shooter may never be found, but whoever they are, they are still guilty. </p>

<h2>3) An individual may or may not be guilty of the crime of which they are charged.</h2>

<blockquote>
  <p><a href="https://thelawdictionary.org/charge/" rel="noreferrer">Charge:</a> the statement of the alleged offense that brings a person to court</p>
</blockquote>

<p>If law enforcement (whether your local traffic cop or the FBI) believes that you are guilty of a crime, they can charge you with committing it.  They may be right. They may be wrong.  But the suspicion of having committed it is enough to charge you.</p>

<p>To continue the traffic example: If an officer sees you running the red light, they can write you a ticket (effectively charging you) for doing so.  They may or may not actually be right (it could have been yellow or malfunctioning, for example), but <strong>law enforcement has the power to charge</strong> regardless.  </p>

<h2>4) A defendant may or may be found guilty and convicted.</h2>

<blockquote>
  <p><a href="https://thelawdictionary.org/conviction/" rel="noreferrer">Conviction:</a> In a general sense, the result of a criminal trial which ends in a judgment or sentence that the prisoner is guilty as charged. Finding a person guilty by verdict of a jury. </p>
</blockquote>

<p><em>This</em> is where the presumption of innocence comes in - the default assumption is that the accused did not commit the crime that they are being charged with, and it's the prosecutor's job to prove otherwise.  If the accused is found to not be guilty of the crime, then they (presumably) didn't do it - it doesn't necessarily mean the crime didn't happen, just that <em>this specific person</em> didn't commit it.</p>

<p>Alternatively, the defendant can be found not guilty for other reasons - the judge or jury can determine that the crime didn't take place, took place but was justified, or the defendant wasn't in their right mind at the time.  </p>

<p>On the other hand, if they are found guilty, they're convicted and sentenced to whatever an appropriate punishment is.  </p>

<hr>

<h1>TL;DR</h1>

<ol>
<li>Whether something is legal is determined by the <strong>legislature</strong> when they pass laws.</li>
<li>Someone who commits an illegal act <em>is</em> guilty of doing so, even if they are never charged.  Again, this is determined by the <strong>legislature</strong> when they pass laws.</li>
<li>People are <em>charged</em> with violations of specific laws by <strong>law enforcement</strong>.</li>
<li>Defendants can be <em>found</em> guilty by <strong>the court system</strong>.</li>
</ol>

<p>In other words, only the courts can determine whether a <em>specific individual</em> actually committed illegal behavior, but the behavior is still illegal regardless.</p>

united-states criminal-law due-process