united-states
Is communism illegal in the U.S. because of the Communist Control Act of 1954?
<p><a href="https://en.wikipedia.org/wiki/Communist_Control_Act_of_1954" rel="noreferrer">The Communist Control Act of 1954</a> was designed to protect America from communism.  Among other things - it made membership in the communist party illegal.  An Arizona judge ruled it was unconstitutional in 1973 (but the supreme court didn't).</p>
<p>Does this mean people could be arrested assuming they are in the right juristdiction for</p>
<ol>
<li><p>Joining the communist party in an American college years after the fact?</p>
</li>
<li><p>Immigrating from a communist country where party membership is either very encouraged or mandatory?</p>
</li>
</ol>
<p><strong>EDIT</strong></p>
<p>It would almost certainly be declared unconstitutional eventually.  Would this be at the hearing after the arrest?  What prevents someone from using this to harass people, and arrest a new group every few months?</p>
<p>For example - a college student is arrested for joining the communist party and taken to jail.  What would the process be to drop the charges?  Does anything happen to the arresting officer?</p>

<p>A person cannot be arrested unless they are suspected of having committed a criminal offense. The <a href="https://www.law.cornell.edu/uscode/text/50/chapter-23/subchapter-IV" rel="nofollow noreferrer">Communist Control Act</a> does not create a criminal offense of being a communist, instead <a href="https://www.law.cornell.edu/uscode/text/50/843" rel="nofollow noreferrer">§843</a> states that a communist</p>
<blockquote>
<p>shall be subject to all the provisions and penalties of the Internal
Security Act of 1950, as amended [50 U.S.C. 781 et seq.], as a member
of a “Communist-action” organization.</p>
</blockquote>
<p>But those provisions concerning <em>communist-action</em> were <a href="https://www.law.cornell.edu/uscode/text/50/chapter-23/subchapter-I" rel="nofollow noreferrer">repealed</a> in 1993<sup>1</sup>. Therefore, a prosecution would go nowhere.</p>
<p><sup>1 - The statute requiring communists to register was already repealed in 1968</sup></p>
