Can a person be prosecuted for unknowingly possessing illegal computer files?
<p>Today there was a <a href="https://www.theguardian.com/technology/2018/mar/20/child-abuse-imagery-bitcoin-blockchain-illegal-content" rel="noreferrer">news article</a> that claims researchers have found illegal files embedded in the Bitcoin blockchain.  This is a large database-type file that contains a list of all the Bitcoin transactions that have ever happened along with possible "meta-data" and it's claimed that some of this data contains illegal images of child abuse.</p>

<p>Bitcoin power users may have the entire blockchain downloaded locally to their computers, but people do not just browse the file for fun.  It contains transaction data that is parsed by automated bitcoin clients and mining utilities, so you wouldn't expect any user to directly access the database and just browse it.  Everyone's copy is exactly the same, so if illegal content is proved to be in the blockchain, then everyone with a copy possesses the illegal content.</p>

<p>So, the question is...  Could someone be arrested or otherwise "get in trouble" because they have a hidden illegal image on their computer that they do not know about?  Especially since the file is hidden amongst useful data that is required for certain bitcoin tasks that the users do have a legal right to participate in?</p>

<p>Tagging as US because that is my primary concern, but would be interested in other locations.  It was German researchers that have found the material.</p>

<p>There is a federal law, <a href="https://www.law.cornell.edu/uscode/text/18/2252" rel="noreferrer">18 USC 2252</a>, which criminalized distribution and receiving of child porn. One part of the law addresses a person who</p>

<blockquote>
  <p>(1) knowingly transports or ships using any means or facility of
  interstate or foreign commerce or in or affecting interstate or
  foreign commerce by any means including by computer or mails, any
  visual depiction, if— (A) the producing of such visual depiction
  involves the use of a minor engaging in sexually explicit conduct; and
  (B) such visual depiction is of such conduct;</p>
</blockquote>

<p>The next part addresses one who</p>

<blockquote>
  <p>(2) knowingly receives, or distributes, any visual depiction using any
  means or facility of interstate or foreign commerce or that has been
  mailed, or has been shipped or transported in or affecting interstate
  or foreign commerce, or which contains materials which have been
  mailed or so shipped or transported, by any means including by
  computer, or knowingly reproduces any visual depiction for
  distribution using any means or facility of interstate or foreign
  commerce or in or affecting interstate or foreign commerce or through
  the mails, if— (A) the producing of such visual depiction involves the
  use of a minor engaging in sexually explicit conduct; and (B) such
  visual depiction is of such conduct;</p>
</blockquote>

<p>The word "knowingly" is crucial here: it may mean that if you don't know, it's not a crime. The wording is not completely clear, in that maybe the law only says that you have to know that you received and don't have to know anything about the item that you received. So it is up the the Supreme Court to say exactly what that means. In <a href="https://supreme.justia.com/cases/federal/us/513/64/case.html" rel="noreferrer">US v. X-Citement Video</a>, Inc., 513 U.S. 64, they did. The court held that "knowingly" does not just mean that you know you are receiving or distributing, because that would yield absurd results such as that a retail druggist who returned a roll of film unprocessed would be guilty of distributing child porn, just in case the film contains child porn. As the court says, "We do not assume that Congress, in passing laws, intended such results".</p>

<p>There is a general constitutional presumption that any crime has a scienter requirement (<a href="https://supreme.justia.com/cases/federal/us/342/246/case.html" rel="noreferrer">Morissette v. United States</a>, 342 U. S. 246, <a href="https://www.law.cornell.edu/supct/html/92-1441.ZO.html" rel="noreferrer">Staples v. United States</a>, 511 U. S. 600): "the standard presumption in favor of a scienter requirement should apply to each of the statutory elements that criminalize otherwise innocent conduct". The court rejects the narrow interpretation that "knowingly" just applies to the verb, and "This interpretation is supported by the canon that a statute is to be construed where fairly possible so as to avoid substantial constitutional questions".</p>

<p>There are also state laws which are untouched by X-Citement, which may make possession of child porn a strict liability offense. <a href="http://app.leg.wa.gov/rcw/default.aspx?cite=9.68a&amp;full=true#9.68A.001" rel="noreferrer">Washington state law</a> is written so that you have to know or intend ("Knowingly develops, duplicates, publishes, prints, disseminates, exchanges, finances, attempts to finance, or sells a visual or printed matter that depicts a minor engaged in an act of sexually explicit conduct as defined in RCW 9.68A.011(4) (a) through (e)" or "Possesses with intent to develop, duplicate, publish, print, disseminate, exchange, or sell any visual or printed matter that depicts a minor engaged in an act of sexually explicit conduct as defined in RCW 9.68A.011(4) (a) through (e)".)</p>

<p>The <a href="http://apps.leg.wa.gov/rcw/default.aspx?cite=9a.44.079" rel="noreferrer">statutory rape law</a> on the other hand has no requirement pertaining to knowledge or intent</p>

<blockquote>
  <p>(1) A person is guilty of rape of a child in the third degree when the
  person has sexual intercourse with another who is at least fourteen
  years old but less than sixteen years old and not married to the
  perpetrator and the perpetrator is at least forty-eight months older
  than the victim.</p>
</blockquote>

<p>I don't know whether some state's statute was written without a "knowingly" requirement.</p>

united-states internet software child-abuse cryptocurrency