What is the US constitutional basis for impeaching, trying and barring from future presidency a former US president?
<p>What is the US constitutional basis for the following actions?</p>
<ol>
<li>Impeaching and trying a former US president?</li>
<li>Barring a former US president from elected a president in the future?</li>
</ol>

<p>I would argue the Constitutional basis of these actions would be the Constitution itself, namely Article II, Section 4:</p>
<blockquote>
<p>The President, Vice President and all civil Officers of the United States, shall be removed from Office on Impeachment for, and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors.</p>
</blockquote>
<p>and Article I, Section 3, Clause 7:</p>
<blockquote>
<p>Judgment in Cases of Impeachment shall not extend further than to removal from Office, and disqualification to hold and enjoy any Office of honor, Trust or Profit under the United States: but the Party convicted shall nevertheless be liable and subject to Indictment, Trial, Judgment and Punishment, according to Law.</p>
</blockquote>
<p>Note also, that as Hamilton explained in the Federalist Papers, the Impeachment process was a check brought over from England (it predated the formation of Britain by several centuries) as a check on Executive (read Monarchal) power of royal appointments, including Judges.</p>
<p>So, to answer your questions directly:</p>
<ol>
<li><p>Serving out one's term or resigning is not a shield to impeachment, otherwise one could simply play &quot;whack-a-mole&quot;, appointing the same individual repeatedly (which is also why future barring of the individual from governmental office is an option). The purpose of impeachment is, per Hamilton, to react to &quot;political crimes&quot;; &quot;mundane&quot; crimes are to be handle by the normal judicial system. Nixon did famously resign rather than be impeached, but he was barred from running again anyway, having served two terms as President. Congress at that time chose not to continue the impeachment process after his resignation (note that disqualification is an option, but not required, punishment that can be levied by Congress in the event of impeachment).</p>
</li>
<li><p>See Article I, Section 3, Clause 7, quoted above.</p>
</li>
</ol>

<p>The issue is unclear.  Article II, Section 4 of the constitution authorizes the removal from office of &quot;The President, Vice President and all civil Officers of the United States&quot; on &quot;Impeachment for, and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors.&quot;  Article I, Section 3 specifies that &quot;Judgment in Cases of Impeachment shall not extend further than to removal from Office, and disqualification to hold and enjoy any Office of honor, Trust or Profit under the United States&quot;.</p>
<p>There is no specific provision allowing impeachment of, or an impeachment trial of a former holder of such an office.</p>
<p>The practice has been for the Senate to first vote on each article of Impeachment, and if and only if it voted to convict on any article, to then vote on whether to add disqualification from office to the judgement.</p>
<p>Several constitutional scholars have recently been quoted in the press to the4 effect that this means that a judgement of disqualification, when one is imposed,  is always imposed on a former office holder, as the conviction has already occurred at that point. Others have argued that the judgement is a single transaction, and it is not final until all the Senate votes are concluded, and so the person remains an office holder when the vote on disqualification is held. No court has ever addressed this issue.</p>
<p>There are two precedents for holding a Senate trial (or at least a Senate Vote) on a bill of impeachment after the office holder had, in one case, resigned, and in the other case, been removed from office by other means. In neither case did the Senate vote to convict. In neither case did the Senate explicitly reject the impeachment <em>because the person was no longer in office</em>, although in each case some senators favored that view. Neither case followed quite the same course of events as the recent impeachment of then-President Trump. Neither case was of a President: one was of a Senator, the other of a cabinet Secretary. Neither case was at all recent.</p>
<p>The House and Senate are, as another answer points out, constitutionally empowered to set their own procedures, although not to expand their constitutional powers. When the House voted to impeach Trump, he was the sitting President and they were clearly within their powers. The Senate is now debating what to do with the articles of impeachment passed by the House, including the issue of the constitutionality of holding a trial on them. There is no precedent for a US court overriding the Senate on any question of Impeachment. The constitution gives the Senate &quot;sole power&quot; to try all impeachments. If the Senate does not vote to convict, that should end the matter. If it votes to convict (which now seems unlikely) and then votes to disqualify Trump from future office, Trump could perhaps challenge that disqualification in court. That would require overruling or distinguishing <em>Nixon v US</em> (which was about a Judge Nixon, not President Nixon). How that might play out no one can reliably predict at this time. It is not a likely chain of events.</p>

us-constitution impeachment