Is probable cause of a crime necessary for a subpoena to be issued?
<p>In order to get a subpoena, wouldn't the prosecutor have to show probable cause that a crime was committed?</p>

<p>According to news outlets (<a href="https://www.nytimes.com/2018/03/15/us/politics/trump-organization-subpoena-mueller-russia.html?mtrref=www.reddit.com&amp;gwh=927D10936AF7C4B1E08A4078F72D54BD&amp;gwt=pay" rel="nofollow noreferrer">example</a>), Mueller has subpoenaed a Trump organization.</p>

<p>I did some research and the answer seemed to be 'yes', but I was talking it over with a friend of the family who took some law classes and the answer was 'not necessarily'.</p>

<p>So is probable cause that a crime was committed necessary for a subpoena to be issued?</p>

<p>A grand jury subpoena needs to not be oppressive or unreasonable: see <a href="https://supreme.justia.com/cases/federal/us/498/292/case.html" rel="nofollow noreferrer">US v. R Enterprises</a>, 498 US 292. The purpose of a grand jury is to determine if there is probably cause: "the Government cannot be required to justify the issuance of a grand jury subpoena by presenting evidence sufficient to establish probable cause, because the very purpose of requesting the information is to ascertain whether probable cause exists". The court held that</p>

<blockquote>
  <p>The unique role of a grand jury makes its subpoenas much different
  from subpoenas issued in the context of a criminal trial. Thus, this
  Court has held that a grand jury may compel the production of evidence
  or the testimony of witnesses as it considers appropriate, and that
  its operation generally is unrestrained by the technical procedural
  and evidentiary rules governing the conduct of criminal trials</p>
</blockquote>

<p>Also note that</p>

<blockquote>
  <p>The grand jury's investigatory powers are nevertheless subject to the
  limit imposed by Rule 17(c), which provides that "the court on motion
  made promptly may quash or modify the subpoena if compliance would be
  unreasonable or oppressive" (emphasis added). Since a grand jury
  subpoena issued through normal channels is presumed to be reasonable,
  the burden of showing unreasonableness, as the above language
  indicates, must be on the recipient who seeks to avoid compliance</p>
</blockquote>

<p>So the bar is lower for a grand jury investigation, such as this one.</p>

subpoena