During the Rittenhouse trial I was surprised to learn there's a legal concept called Mistrial with Prejudice. Are there any statistics on how often this happens in Federal and State courts in the US for criminal law trials?

  • I imagine someone has statistics somewhere, but I'm comfortable saying that dismissals with prejudice happen all the time in civil cases, and much more infrequently in civil cases.
    – bdb484
    Nov 18 at 19:35
  • @NateEldredge updated question to be more clear Nov 18 at 19:45
  • I found the following document focusing on hung juries in state courts, including conviction/acquittal/mistrial rates, but it only seems to break down between "hung jury" and "other mistrials". The hung jury stuff gets broken down a fair bit more, being the focus of the article, but "other mistrials" doesn't seem to go into with/without prejudice or other matters. Nov 18 at 21:08
  • Ok, yeah, "mistrial" is a completely different thing than "dismissal". Deleting previous comment. Nov 18 at 22:27
  • Mos dismissals are not mistrials, and in a US criminal cases I think most but no all mistrials are with prejudice. Nov 18 at 22:35

There are not comprehensive statistics that are maintained on this at either the federal level, or in any U.S. state.

It would not be possible to determine this from PACER records in federal court, or from state court online filing system records in many state courts, because both of those systems are geared towards tracking document filings in the court system. But a motion for mistrial in a criminal case, while it can be filed in document form, would frequently be made orally, in open court, instead. Sometimes an oral motion and its resolution would be reflected in written court minutes or a minute order, but often it would not.

In criminal cases, more generally, the proportion of motion practice that is conducted orally in open court, rather than through filed written documents is great. Also, even in civil cases, during trials, motions are frequently made orally, rather than in writing.

Oral motions are part of the court record on appeal, and can be found in a transcript, but even if you had lots of transcripts for cases (something that no trial court system in the U.S. routinely makes available to non-parties), you would have to pour over the entire undifferentiated transcript to find instances in which motions are made, which in a multi-day trial is a daunting task. And, it typically takes weeks after a trial from which there is an appeal, for an official transcript to be prepared. Written transcripts are frequently never prepared at all in cases that are not appealed. Instead, there are an audio recording and the court reporter's shorthand notes that are stored until a transcript is ordered or the time during which a transcript could be needed has expired.

There are probably law review or social science academic journal articles in which this issue has been studied in a small number of courts and statistics were gathered from a modest sized sample to look at the issue. But there probably aren't many, and many of the articles are probably fairly old.

It would be easier to study the number of appellate opinions in which a denial of a motion for mistrial with prejudice was appealed. But, if it is granted, no appeal is possible, so this would be a biased sample (and would not include cases where no appeal was filed from a conviction after such a motion was made and denied). Another difficulty is that only a small share of all criminal appeal decisions are published, and even if you could get all of the unpublished decisions, many unpublished decisions assume a familiarity with the case that non-parties would not have and are skimpy on factual recitations as a result, making them difficult to analyze.

There are good statistics on the number of acquittals and mistrials granted in criminal cases. Even though there are probably not official statistics, it may even be probably possible to find decent research articles on the share of acquittals and mistrials that are due to motion practice, rather than a jury verdict of acquittal or a sua sponte ruling of a judge. A significant subset of these cases would involve mistrial with prejudice motions (although there are other grounds upon which someone can be acquitted in motion practice in criminal trials, and there are other grounds upon which a mistrial could be granted in a criminal trial).

So, in short, there is some data out there from which one could cobble together some educated guesses and estimates, but the kind of data your question is looking for does not exist and would be very difficult to compile comprehensively or even for a large sample.

It is also worth noting that this is a percentage which even if you knew it in one state or in the federal court system, is likely to be quite different in a different court system.

In the same vein, for example, there are almost no grand jury "no bills" in which a grand jury refuses to indict a defendant in the federal court system, but the percentages are in the mid-double digit percentages in some Southern U.S. counties. Local practice norms and customs and differences in the relevant criminal court rules, influence these numbers a great deal.

Another key difference would involve the character and length of the trials involved. There are going to be more mistrial motions in murder cases that last many days, than there are in half day long traffic offense jury trials. If you can't break down the numbers by case type, data from numerous but trivial trials will drown out the data on what is typical in the kind of cases you are really interested in knowing about.

As a practical matter, asking an experienced practitioner in criminal cases for a general impression of how common something is and a vague guess of its order of magnitude frequency would probably be a more reliable way to get good information. I'm certainly not such a person.

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