How can felons be denied Constitutional rights?
<p>The 2nd Amendment grant all people a right to bear arms:</p>

<blockquote>
  <p>A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.</p>
</blockquote>

<p>However felons are somehow denied that right.  Ignoring whether it would be desirable to have armed felons, then why would that not be unconstitutional? </p>

<p><a href="https://www.law.cornell.edu/supct/html/07-290.ZS.html" rel="nofollow">District of Columbia v. Heller, 554 U.S. 570 (2008)</a>, majority opinion, written by Justice Antonin Scalia:</p>

<blockquote>
  <p>Like most rights, <strong>the right secured by the Second Amendment is not
  unlimited</strong> ... Although we do not undertake an exhaustive historical
  analysis today of the full scope of the Second Amendment, <strong>nothing in
  our opinion should be taken to cast doubt on longstanding prohibitions
  on the possession of firearms by felons</strong> and the mentally ill, or
  laws forbidding the carrying of firearms in sensitive places such as
  schools and government buildings, or laws imposing conditions and
  qualifications on the commercial sale of arms.</p>
</blockquote>

<p>(emphasis mine)</p>

united-states us-constitution second-amendment