Limits on sources of fact or law for a court (incl. appeal)
<p>There are specific rules for introducing sources of fact in a normal (first-instance) trial, either through evidence or through witnesses, with constraints around hearsay, etcetera. A fact (or an alleged fact) introduced or referred to in a trial needs to be sourced following these rules, or be disregarded.</p>
<p>It would also seem logical to me (although I'm not sure about it) that since a suit where one party fails to attend entails a default judgement in favor of the other party, then a judge must only apply a law if it has been invoked by at least one party in the trial (when it comes to sentencing I mean, not on procedural grounds during the trial itself). Is that inference true ?</p>
<p>It seems to me (as said in the movie On the Basis of Sex) that a US court of appeals and the Supreme Court work like the french Court of Cassation, in that it only (re)judges questions of law, and not questions of facts. If so, does the same standard of only applying sources of law mentioned during the trial apply there ?</p>
<p>I'm asking the question after having read the infamously leaked Alito opinion from Dobbs v. Jackson, which ends by exhaustively listing old state abortion laws. Although I didn't read the transcript of the hearing that thoroughly, I doubt all these sources of law (or of fact, depending on how you look at it, since the opinion cites them as evidence and does not seek to apply them) were all cited by the party arguing against Roe.</p>
<p>If judges (and justices) are not bound by what law(s) and which facts have been cited by the parties, what is the limit on how judges can do the parties' job, inventing their legal arguments for them ? If they are not, how could a poorly-defended case be prevented from setting a terrible jurisprudence precedent ? Final question, is there a difference between how these rules bind judges and justices (i.e in Courts of Appeals vs in the Supreme Court) ?</p>

<p>David Siegel's answer correctly explains how appellate courts consider laws and arguments not addressed in the courts below. To clarify on the comparison to the Court of Cassation, though:</p>
<p>A trial court is generally limited to considering the facts that are properly introduced by the parties, though a court may also take &quot;judicial notice&quot; of certain facts that are highly unlikely to be disputed.</p>
<p>On review, courts of appeal are generally limited to facts supported by the evidence in the trial-court record, though they may also take judicial notice of other facts. A party is generally unable to introduce new evidence during an appeal.</p>
<p>It is not correct that an appellate court will not review factual determinations, as those reviews probably happen in more cases than not. But -- just as with legal determinations -- those reviews can happen with varying levels of deference.</p>
<p>For instance, if a case is tried to a jury, an appellate court will be exceedingly deferential to the jury's factual determinations, on the theory that the jury is best positioned to evaluate the evidence, gauge credibility, make reasonable inferences, etc. A judge who makes a factual determination based on in-court testimony will enjoy a similar measure of deference.</p>
<p>But if a court makes a factual determination based only on documents submitted in support of a motion, or otherwise lacks an opportunity to evaluate a witness in person, the appellate court will be more open to different interpretations of the evidence.</p>
<p>Legal determinations are likewise subject to varying levels of deference.</p>
<p>At one end is the abuse-of-discretion standard. If a trial court determines that evidence is admissible or inadmissible, for instance, an appellate court will apply the abuse-of-discretion standard, which (to oversimplify) asks not whether the ruling was incorrect under the controlling law, but whether the ruling was reached without regard to the controlling law.</p>
<p>On the other end is <em>de novo</em> review, in which the appellate court gives virtually no deference to the trial court and undertakes its own independent legal analysis.</p>
<p>Perhaps even more deferential is plain-error review, which asks (to oversimplify) whether the trial court's error is so apparent that it barely needs to be debated. If the error is obvious enough (and satisfies several other criteria), the appellate court <em>may</em> reverse the trial court.</p>

<p>US courts are not limited to considering laws cited or introduced by the parties. Judges can, and often do, base decisions on laws and court decisions (precedents) that the parties did not mention. This is true at both the trial level and at the appellate level, including in Supreme Court opinions.</p>
<p>Nor are the courts limited to the legal arguments made by the parties, they can introduce novel arguments and decide on that basis, although this is somewhat rare.</p>
<p>The Supreme Court often declines to address an <strong>issue</strong> not raised by the parties, requesting re-argument on the issue if it is thought vital. But this is not required, and the Court can and does make decisions based on an issue not raised by the parties if it thinks proper, particularly where it deems the result sufficiently clear cut that argument would add little.</p>
<p>Note that an issue is more general than any particular law or precedent.</p>
<p>On matters of fact, appellate courts do not normally acept or consider evidence that was not presented at the trial level. Where a court holds that evidence was improperly excluded, or improperly admitted, <strong>and</strong> that such an error probably affected the decision, the court most often sends the case back for retrial, rather than judging what the outcome would have been with the evidence adjusted.</p>
<p>Appellate courts can and do consider whether the evidence supports the judgement, and if &quot;no reasonable finder of fact&quot; could have come to the decision that was arrived at in the trial, may overturn the verdict.</p>
<p>Appellate courts can and do take &quot;judicial notie&quot; of matters commonly and widely known.</p>

united-states appeal law-in-fiction