When is it encumbent on a court to rule on arguments not raised by the defense?
<p>Usually a court will not make a ruling using an argument which the parties to the case have not raised. <a href="https://law.stackexchange.com/questions/37104/are-judges-limited-in-their-reasoning-to-arguments-raised-by-the-parties">This subject has been discussed on this site previously.</a> However, I would argue that this legal principle only applies to substantive arguments, in other words when the argument involves interpretation of evidence. When an argument involves no interpretation and is based either on logic alone, or on evidence which admits of no alternative interpretations, then I would argue that a judge has the right to intervene. The question here is when does that right become a duty? Also, is there a Latin or other terminology that applies to this situation?</p>
<p>So, as an example of this, imagine a situation where a judge has previously presided over a criminal case in which a particular defendant was acquitted by a jury. Later, that same defendant is brought before the judge again on the same charge. For whatever reason, the defending attorney fails to argue that his client should be not be tried twice on the same charge. However, the judge knows for a fact that this is the case because he presided over the previous trial himself. Is it encumbent on the judge to dismiss the charge?</p>
<p>Here is another example involving logic alone. Imagine that a defendant is tried on a criminal charge and convicted by a jury on that charge. Before sentencing however, the judge discovers that the legislature had repealed the law under which the defendant was charged several weeks before the alleged crime had occurred. At this point the judge realizes that he made an error at the arraignment by allowing the case to come to trial at all. Is it now encumbent on the judge to set aside the jury verdict and dismiss the charge?</p>

<h2>Never</h2>
<p>A common law judge’s (and jury’s) task is to resolve the case that the parties choose to bring based on admitted evidence.</p>
<p>Common law is adversarial, civil law is inquisitorial. A common law judge’s (or tribunal’s) role is to decide the parties’ dispute; unlike a civil law judge they have no (direct) interest in finding the truth.</p>
<p>A judge that decides on the basis of facts not in evidence or law that the parties have not had the opportunity to be heard on has not afforded them <a href="https://en.m.wikipedia.org/wiki/Natural_justice" rel="nofollow noreferrer">natural justice/procedural fairness</a>. If they do that, they have fallen into reviewable error. Whether such an appeal is successful will turn on if doing it right rather than wrong might have made a difference.</p>
<p>The judge’s (or jury’s) personal knowledge is <strong>not</strong> evidence.</p>
<p>However, their hands are not tied. They can draw such matters to the parties’ attention and call for submissions. This meets the requirements of procedural fairness: if the parties’ want to say something or introduce evidence of the matter, they can and it is then properly before the forum. If they don’t, they don’t. Nevertheless, the judge needs to be impartial in this: they cannot become an advocate - it’s better to say “tell me about X” rather than “I think this about X”.</p>
<p>For your examples:</p>
<ol>
<li>The judge calls for submissions on the identity of the defendant and the identity of the defendant in the other case and if the charges are identical.</li>
<li>The judge would go to the parties, advise them if the situation and ask if anyone would like to file a motion for the conviction (for that’s what it is once the verdict is delivered) to be set aside. They would probably withhold sentencing until the parties’ decided if they want to and the motion, if any, was resolved.</li>
</ol>

united-states common-law jurisprudence