Evidence may be inadmissible, but that doesn't necessarily mean it will be ineffectual in its influence of the jury, and the judge. For example, evidence proving a horrendous crime done by the accused, that has been rendered inadmissible via e.g. the exclusionary rule, would still of course have an emotional impact on the judge and jury. That would mean that inadmissible evidence wound up affecting the trial despite its inadmissibility.

So, I have two questions:

  1. What are the consequences for the person that brought this inadmissible evidence to light? I expect this may vary depending on whether this person is a state official or not, and their involvement in the case.

  2. Will the case end as a mistrial, or will a new trial begin, due to the unlawful influences introduced?


1 Answer 1


This answer is based upon general principles of criminal procedure in the United States which are quite similar in most states, although not necessarily exactly identical. The answer is likely to be different in other jurisdictions.

If inadmissible evidence is offered by the prosecution and admitted at trial, this is a ground upon which the defense can move for a mistrial (which due to double jeopardy amounts to an acquittal), or upon which the defendant can appeal the conviction of the jury, if convicted.

Acquittals of a defendant at trial cannot be appealed by the prosecution.

But, to appeal, the error in admitting inadmissible evidence must be contemporaneously objected to by the defendant's lawyer (or the defendant if the defendant is not represented by counsel), or the admission of the evidence must be "plain error" (which is very rarely met on evidentiary issues). If the defendant's lawyer doesn't promptly say "I object" that ground for contesting a conviction is usually lost.

Even then, the standard of review on appeal is whether the judge abused the judge's discretion in admitting the evidence, not whether the appellate court would have ruled the same way if presented with that evidentiary question.

Also, even if there is an error, a conviction on a particular count will not be overruled if the error was "harmless", which is to say that there is a reasonable possibility that admitting the inadmissible evidence caused the defendant to be convicted of that count. Often, if the evidence is overwhelming, or the inadmissible evidence wasn't that prejudicial, a conviction will be affirmed notwithstanding the admission of inadmissible evidence.

Sometimes harmless error is evaluated considering all of the errors at trial as a whole, rather than individually, in addition to all of the other evidence admitted at trial.

If an evidence issue can be foreseen and is central to the case (e.g. suppression of evidence of possession of drugs in a drug possession case), the issue of the admissibility of the evidence will often be resolved in a pre-trial hearing and subject to appeal then, prior to trial, rather than being resolved in the trial itself where the prosecution has no right to appeal, and the defendant risks conviction if the ruling goes against the defendant.

If the conviction is overturned on appeal, the usual remedy is to remand the case to the same judge to conduct a new trial with a new jury, in a manner consistent with the appellate court's rulings.

  • [1/2] Thanks, this is quite informative. However, I still have some questions. (1) "(...) not whether the appellate court would have ruled the same way if presented with that evidentiary question." I don't get this part, why would the review be about this and what does evidentiary question mean in this case? (2) What if the evidence was admitted into court without the judge's knowledge? Then, a review couldn't be about whether the judge's discretion was abused. However, perhaps any trial where evidence is admitted without the judge's knowledge is a mistrial?
    – user110391
    Commented Mar 2, 2022 at 0:45
  • 1
    @user110391 I think most of those could be good, separate Q&A's in their own right. Commented Mar 2, 2022 at 1:55
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    @user110391 (1) Most evidence decisions are judgment calls involving applying a quite vague rule of evidence to facts that can be characterized in one than one way. If reasonable judges could disagree with the right answer, the trial judge's ruling is considered to be correct. It is that way because that is what the common law of appellate review says it is. Whether the exclusionary rule applies, e.g., depends upon the question of whether there was probable cause to search. Only if no reasonable judge could find that there was probable cause will it be found to be error to admit the evidence.
    – ohwilleke
    Commented Mar 2, 2022 at 21:21
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    @user110391 (2) "What if the evidence was admitted into court without the judge's knowledge?" In a jury trial, I can't envision a scenario in which this could happen in the face of a timely objection by defense counsel.
    – ohwilleke
    Commented Mar 2, 2022 at 21:23
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    @user110391 (3) "What kind of considerations go into whether the appellate court decides to go for a retrial or acquittal?" There is a retrial unless there is no possible way that there could be a conviction upon retrial. "What could make a appellate court decide to retrial with a new judge?" Grossly defiant behavior by the trial judge following a first remand from an appellate reversal, or if the judge is no longer a judge in that court at the time of the remand for any reason. "Can an appellate court decide to retrial with the same jury?" No.
    – ohwilleke
    Commented Mar 2, 2022 at 21:25

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