Say you are convicted of murder, for example. When you go to court, and plead not guilty under oath, isn't that perjury, since you're lying by saying that you didn't do it?

"Perjury is a criminal act that occurs when a person lies or makes statements that are not truthful while under oath." Source

You are making a statement that isn't true (you aren't guilty), while under oath, so why isn't this perjury? If this is then does that mean that if you are guilty, and you don't plead guilty that you are committing perjury?

  • 2
    Depending on your point of view, you might consider the difference between a plea bargain and the sentence delivered after a successful prosecution as the penalty for this kind of "perjury".
    – Patrick87
    Commented May 24, 2017 at 0:02
  • You're not saying "I'm innocent." You are saying "I'm not guilty." I believe there's a difference.
    – mark b
    Commented Jul 7, 2019 at 19:40

5 Answers 5


Perjury is not 'not telling the truth'. It requires (in most jurisdictions) being proven to have deliberately lied under oath. As Xavier pointed out, you are not on oath when entering a plea (among other reasons, you would be required to incriminate yourself).

Secondly, "I am not guilty" could mean anything from "the prosecution wrongly think that what I did is illegal" to "this law is unconstitutional" even if the facts are not in dispute; either may be mistaken without being a lie. If the facts are in dispute, the jury will have to deliver a verdict that implies (it does not state, let alone prove) that they disbelieve one party; deliberate falsehood, whether by a defendant or a police officer, would be several steps beyond that.

  • It is also worth observing that in U.S. criminal law practice, it is rather rare for a defendant to actually testify under oath as a witness in his or her own defense, especially if the offense is serious and the defendant has a criminal record that would be admissible in evidence if the defendant did testify.
    – ohwilleke
    Commented Jan 25, 2022 at 22:14
  • Also, a plea is not a statement. When you plead "not guilty," you are not asserting that you are not guilty, but requesting that the court and/or jury find you not guilty, so a plea could not be perjury even it defendants were under oath, because it's not a lie. But if it makes you uncomfortable to affirmatively plea "not guilty," you can refuse to say anything at all, which in the US must be interpreted as "not guilty" plea. Commented Aug 2, 2023 at 13:59

Without going to specific jurisdictions perjury is "the offence of willfully telling an untruth or making a misrepresentation under oath". It therefore requires an untruth intentionally made with the intent to deceive while under oath - not stated in this definition is that the deceit must be material to the matter being decided.

First, pleas are not given under oath and second, a not guilty plea simply means "the prosecution does not have enough evidence to convince the jury beyond reasonable doubt that I committed this specific crime I am accused of in the specific particulars alleged ... I think" which is hardly a position that can be a lie.

The fact that a jury or judge does not believe a witness is not evidence that that witness has committed perjury. The witness could believe an untrue thing and be faithfully reporting their untrue belief. The witness may miss-remember an event and be faithfully reporting that mistaken recollection. The witness could be telling God's own truth and simply be unable to convince the jury or judge of this - that is, they are wrong not to believe.

To prove perjury the state has to provide sufficient evidence that the witness knowing told a material lie with the intention of deceiving the court or tribunal. This is not easy.

There is an expectation that defendant's will use any and all methods in their defense. Even methods that are, strictly speaking, not legal. It is the prosecution's duty to prove guilt beyond reasonable doubt - the defendant has to prove nothing. If the prosecution's case is so weak that the defendant lying under oath is enough to derail it then it was too weak to take to trial!

In addition, prosecutors have a duty to the public to use limited resources (like their own and the court's time) judiciously. Is it really in the public interest to pursue a convicted murderer who has just been given a 12 year sentence on a charge of perjury for which the punishment will be 12 months served concurrently?


Pleading not guilty at a preliminary hearing would not make it perjury, as you are not under any type of oath to speak the truth. In this case, if it were even close to perjury, you would have to testify against yourself. Then you would be under an oath to speak the truth.


A plea is not a statement or claim (other than stating that one wishes to have a trial, and presumably that claim is true). Everyone has a right to a trial. That right can be waived. "Pleading guilty" is simply a term that is used to refer to this waiver. "Pleading not guilty" is what not waiving the right is called. It is not making any claim as to one's guilt. Requiring someone to answer whether they are guilty or innocent would be a violation of the Fifth Amendment. Accusing someone who pleads not guilty, and is later convicted, of perjury is like calling a coach a liar because they asked for a call to be reviewed and the call was upheld.


As others have said, entering a not guilty plea isn't done under oath so it doesn't fall foul of s.1 of the Perjury Act 1911:

If any person lawfully sworn as a witness or as an interpreter in a judicial proceeding wilfully makes a statement material in that proceeding, which he knows to be false or does not believe to be true, he shall be guilty of perjury...


A defendant can, if they wish, give evidence in their own defence which follows the same rules and procedures as with all other witnesses - including taking the oath (or affirmation) so it is possible for them to commit perjury if they deliberately lie within the meaning of section 1.

That said, the Crown Prosecution Service advises caution:

Perjury by a Defendant

If a defendant is convicted despite giving perjured evidence, the decision to prosecute must take note of the sentence imposed for the original offence. If you think a conviction for perjury is unlikely to result in a substantial increase in sentence, then the public interest probably does not require a prosecution.

Consider also the possible consequences to the original conviction of an acquittal of the defendant on a charge of perjury arising out of the earlier proceedings. Prosecutors should, therefore, be satisfied that the evidence of perjury is exceptionally strong before instituting proceedings.

Evidence of premeditation is an important factor in coming to a decision on whether or not to prosecute. If the defendant's deceit has been planned before the hearing as opposed to arising on the spur of the moment during cross-examination, the public interest in prosecuting will be stronger.

Where a defendant is acquitted, wholly or partly because of false evidence given by him or her, a prosecution for perjury might be appropriate. Where there is clear evidence of perjury, which emerges after the trial, and which goes to the heart of the issues raised at the trial, a prosecution for perjury may be appropriate. A prosecution should not be brought, however, where it may give the appearance that the prosecution is seeking to go behind the earlier acquittal: see dicta by Lord Hailsham L.C. in D.P.P. v Humphrys [1977] AC.

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