If you were tried for murder and acquitted - then you go out and publicly admit that they were wrong, you did actually murder that person. Where is the justice in not being able to be tried again in those circumstances? There is now no doubt that you were in fact guilty - why tie the court/police's hands?

For example, the case of Emmett Till, where the murderers freely admitted that they did it after the fact, and could not be tried again.

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    Note that double jeopardy does not bar a civil lawsuit.
    – ohwilleke
    Commented Jul 18, 2023 at 14:41
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    This needs a country tag. Here in the UK, "double jeopardy" is not a concept. Commented Jul 19, 2023 at 10:34
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    You know there have been people who confessed who didn't do it right?
    – Joshua
    Commented Jul 19, 2023 at 19:38
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    Note that double jeopardy doesn't protect you from civil suits. OJ was found not guilty of murder in criminal court, but then he lost the wrongful death suit in civil court. So it's generally not a good idea to announce that you pulled one over on the justice system.
    – Barmar
    Commented Jul 20, 2023 at 12:31
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    The notion that an admission of guilt overrides any other type of evidence has a long history but is very questionable. There are many many examples of people admitting to crimes they didn't commit for various reasons so publicly admitting something doesn't mean there isn't any doubt. On the other hand, what if some other incontrovertible evidence emerges? The question boils down to how new evidence and the Non bis in idem principle are handled in a jurisdiction, public admission is a bit of a red herring.
    – Relaxed
    Commented Jul 20, 2023 at 12:40

4 Answers 4


In the United States, prohibition against double jeopardy is a constitutional protection. As long as one was actually at jeopardy for an offence by a particular sovereign, that sovereign may not subsequently prosecute the accused for the same wrong. In other jurisdictions, such as the U.K., it has a less strict form, even though generally, special pleas of autrefois acquit would be available.

It is also not the case that after an apparent "confession" in public that there is "no doubt" about a person's guilt. No evidence is "certain" in law without being tested in court.

Also, you propose:

you were tried for murder and acquitted - then you go out and publicly admit that they were wrong, you did actually murder that person

This does not put the acquittal into question. The prosecution failed to prove the case beyond a reasonable doubt. This means at law that one is deemed to be not guilty. Your scenario does not show that the trier of fact was "wrong" about the prosecution failing to prove its case beyond a reasonable doubt. This is not an avenue by which the prosecution can challenge an acquittal. If a properly instructed trier of fact finds that that the prosecution did not prove its case beyond a reasonable doubt, this conclusion is unassailable.

You ask "where is the justice?" The justice of a system is assessed by its application across the totality of cases. Given that a system of prosecuting and judging that is run through humans will inevitably produce errors, the law has developed to promote a measure of "justice" across the entirety of the cases that are disposed of by the court rather than to futilely attempt to ensure the "correct" result in every particular case.

The rule against double jeopardy has arisen out of this systemic concern for justice. It does not purport to secure the "correct" result in every case.

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    regarding the certainty of guilt - I could give a more extreme theoretical example where the murderer produced a videotape of themselves performing the murder (or some other "certain" proof) and double jeapardy would still protect them from prosecution. I'm not debating, though - I understand your point that it is written as it is to cover the majority of cases
    – Jon
    Commented Jul 18, 2023 at 14:46
  • @Jon If such evidence existed, than the prosecutor had the option to wait for it to fall into their custody legally and then take the trial. Yes, the murder would not be convicted immediately, but in most jurisdictions, there is no statute of limitations on murder, thus if it takes 1 year, 20 years, 40 years, or more to get it right, then they have that option.
    – hszmv
    Commented Jul 18, 2023 at 14:49
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    Also to add to Jen's answer, In the Scottish Legal systems, Juries are given the option of three verdicts: Guilty, Not Guilty, and Not Proven. Not Proven has the same result as Not Guilty however, it's rendered when the jury believes that the prosecutor failed to prove the guilt of the defendant convincingly enough for Guilty, not because they defendant was provably innocent. As one Scottish friend of mine described it, it's the jury saying to the defendant "You didn't do it, and you better not do it again!"
    – hszmv
    Commented Jul 18, 2023 at 14:54
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    Interesting. Does this mean that being acquitted of the first trial makes the person free to claim and spread the evidence of his crime and be proud of it with impunity(to some period of time)?
    – justhalf
    Commented Jul 19, 2023 at 7:10
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    @justhalf In principle, though as Ohwilleke has noted double jeopardy protection from a criminal prosecution is no bar to a civil suit or public sentiment. Additionally, in the US most everyone is subject to at least two sovereigns at any given time: a state and the federal government. An acquittal only provides double jeopardy protection against the sovereign that brought the charge; any others that didn't could still in principle file charges, if any are available (e.g. there is no federal crime of murder, though hate crimes, crossing state lines, etc. can create federal jurisdiction) Commented Jul 20, 2023 at 1:09

Just because I believe I’m guilty doesn’t mean I am

All crimes contain elements, each of which must be true for someone to be guilty. Yes, I shot the victim, yes, I intended to kill him, yes, he’s now dead, yes, I believe I’m guilty. But if he died in his sleep just before I pulled the trigger, I’m not.

Confessions can be lies

I know it might shock you, but people are not always telling the truth when they confess to a crime. There are various reasons why someone might do this: mistaken belief, protecting someone else, status etc. Grotesque as it is, in the Emmett Till case, the acquitted men would have received a great deal of status in their community if they had committed the crime - that could be enough incentive for them to falsely confess.

Conflicting objects of the legal system

Justice is only one of the purposes of our legal system. Others include efficiency and finality.

Society can have only as much justice as it can afford - in both time and treasure. Yes, it would be more just if every case reached the correct result but it’s just too damn expensive.

Similarly, the legal process must come to a final and definitive end. It is neither efficient nor just for the process to be never ending.

Finally, in a criminal matter, compared to any given individual, the state has near limitless resources. It’s important not to allow the justice system to become a tool of persecution. You can’t allow the state to keep feeding coins into the slot machine until they hit the jackpot of a jury that agrees with them.

Some jurisdictions do allow retrials in certain situations

The rule against double jeopardy in the USA is a constitutional protection and, unless that changes, it is absolutely prohibited.

Other common law jurisdictions such as the UK and some Australian states allow the rule to be broken for serious crimes (like murder) where there is “fresh and compelling evidence”. An unsworn confession by the accused isn’t very compelling.

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    According to the answers to this question law.stackexchange.com/questions/24615/… if you shoot a dead person you are guilty - of attempted murder.
    – Vorbis
    Commented Jul 19, 2023 at 12:54
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    @Vorbis : but attempted murder often carries drastically different sentences compared to actual murder.
    – vsz
    Commented Jul 20, 2023 at 7:05
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    @vsz yet both would benefit from a re-trial.
    – ave
    Commented Jul 20, 2023 at 14:10
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    "You can’t allow the state to keep feeding coins into the slot machine until they hit the jackpot of a jury that agrees with them." This is what I was taught about Double Jeopardy back in the 1970s.
    – RonJohn
    Commented Jul 21, 2023 at 4:07
  • 1
    @Jon Green v United States 355 U.S. 184 (1957) caselaw.findlaw.com/court/us-supreme-court/355/184.html
    – Dale M
    Commented Jul 22, 2023 at 22:33

In the U.S., the bar against double jeopardy exists because court cases cost money both to the defendant and the tax payer. Since it is the state that can bring criminal cases and the state that has superior resources in evidence gathering, the law was implemented to prevent the state from ruining an innocent person by repeatedly trying them in court at the tax payer's expense. Additionally, it is to prevent the state, having once failed to convince the jury, to retry with another jury and continue to do so until they get a verdict they like.

While there are occasions where Double Jeopardy does not attach, these are exceedingly rare (one of the few times it was done without declaring a mistrial was in a case where the judge in a bench trial was bribed to return a not guilty verdict. Because the defendant was never in a legal jeopardy situation, it was ruled he could be tried again for the same criminal event). Additionally, the State and Federal Government are separate sovereigns for the purposes of Double Jeopardy, and while the Federal Government does not normally try someone who is tried by the state regardless of outcome, it is certainly possible for them to do so as the rules preventing them are policy, not law.

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    I would think that res judicata would be the underlying principal for barring double jeopardy. If the decision of a court can be questioned (other than by an appeals court), then what authority does the court actually have? The idea of double jeopardy has existed since ancient Greek times and I've never seen monetary costs listed as a justification.
    – doneal24
    Commented Jul 18, 2023 at 15:12
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    And as the trials of Jon Gotti illustrate, the state has quite a bit of resources to bring many different types of cases. Double jeopardy is of little concern to the state to get after a perpetual criminal.
    – paulj
    Commented Jul 19, 2023 at 20:19

Another advantage of double jeopardy protection, beyond what has been mentioned already, is that it helps the truth to come out after the trial is over. For example, the murderers of Emmett Till would likely not have freely admitted to the crime had the possibility of criminal penalties still existed. There are several cases where this provides historians information that otherwise would have remained hidden.

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