Compulsory counterclaim rule in states of USA
<p><a href="https://content.law.virginia.edu/faculty/profile/ks3r/1209145" rel="nofollow noreferrer">Prof. Kent Sinclair</a> said in a conference</p>

<blockquote>
  <p>"... over 40 states had adopted a compulsory counterclaim rule."</p>
</blockquote>

<p>but he didn't say their names. Who knows which states have such rule? (I found a table on the web with their names but I can't find them now.)</p>

<p>Advisory Committee on Rules of Court reported on October 1, 2007:</p>

<blockquote>
  <p>The rules in 42 states, the District of Columbia, and the 95 federal
  district courts reflect the judgment of almost all American
  jurisdictions, which have decided in the last 70 years that a
  defendant should bring any counterclaim available against the
  plaintiff as part of the original lawsuit if the counterclaim arises
  out of the same conduct, transaction or occurrence as the plaintiff's
  claim.</p>
</blockquote>

<p><a href="https://i.stack.imgur.com/KnmSX.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KnmSX.jpg" alt="States in which Compulsory counterclaim rule exists 1"></a></p>

<p><a href="https://i.stack.imgur.com/Jn5aE.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Jn5aE.jpg" alt="States in which Compulsory counterclaim rule exists 2"></a></p>

civil-procedure claims