Another answer says, without qualification (emphasis mine): "Lying per se is not illegal. For it to be so, the person lied to has to suffer a detriment that the lier [sic] ought to prevent."

But, are there lies that are considered illegal without any demonstrated detriment?

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    Do you mean to ask whether actual harm is required, or just potential to cause harm? As Kevin shows in his answer I'm sure there are many cases where a lie was caught before harm was done, but a more interesting question might be whether any "harmless" lies can be punished.
    – David K
    Commented Feb 12 at 13:46
  • Do slander, libel, and defamation count as "demonstrated detriment"? It's all reputational and therefore subjective, but those kinds of cases are adjudicated all the time with associated "punishments". Commented Feb 14 at 14:28
  • Where does 'a detriment that the lier [sic] ought to prevent' come from, please? In every-day English, should that not rather be 'ought to have tried to prevent' or 'ought to have prevented'? In legal terms, if the person lied to suffers detriment, how could that not leave the lier open to one or another charge of fraud? From either perspective, how could a lie with no detrimental consequence be subject to punishment? Commented Feb 14 at 23:35

6 Answers 6



For just one of many examples, see s. 52 of Canada's Competition Act, which makes it an offence to display a false or misleading advertisement. Section 52 expressly says that "it is not necessary to prove that ... any person was deceived or misled." In this context, it is the falsehood that is punished, for its own sake.

* This answer is not really about the full scope of s. 52, but to address a comment wondering about parody, subsection (4) avoids parody being caught by the prohibition: "the general impression conveyed by a representation as well as its literal meaning shall be taken into account in determining whether or not the representation is false or misleading in a material respect."



In the wonderfully-named United States v. 11¼ Dozen Packages of Article Labeled in Part Mrs. Moffat's Shoo Fly Powders for Drunkenness, an in rem proceeding, the District Court for the Western District of New York ordered the condemnation and destruction of the packages described in the caption, because they were misbranded. They contained tartar emetic, which induces vomiting and is also poisonous at the dose recommended on the box, and is in no way a legitimate cure or treatment for drunkenness, so the court found that the label was false and misleading, and ordered the packages condemned. The court did note that expert witnesses had testified that tartar emetic was poisonous and potentially harmful, but the final judgment was solely that they were misbranded.

TL;DR: In the United States, drugs whose labels are false and misleading may be subject to condemnation and destruction. There are similar laws applicable to food (see for example United States v. 95 Barrels of Vinegar, which is perhaps an even better example because the product in that case was entirely harmless and it was purely a matter of quality).

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    This is different. It is illogically for someone to be harmed first before a stop is put to it if the substance is known to be dangerous to begin with. Commented Feb 12 at 13:11
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    The real question is "Who in their right mind would say '11¼ dozen' instead of '135?'" Commented Feb 12 at 13:16
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    @stackoverblown But as the answer points out, the final judgment was based solely on the fact that it was misbranded, not that the substance was potentially harmful. That is to say, the court's statement is that the same ruling should apply in similar cases in the future even if the product in question isn't harmful.
    – Idran
    Commented Feb 12 at 14:15
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    This answer seems to assume "harm" means "bodily harm", but the question body also uses "detriment", which I think is quite general. A misbranding of vinegar with regards to its quality could be considered somewhat like fraud, right? That would be financially harmful, because the buyer wouldn't be getting the quality they paid for.
    – JoL
    Commented Feb 13 at 4:56
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    @JoL: Yes, we can reduce this to absurdity. All deception violates Kant's categorical imperative, so all deception is harmful, so the question is self-contradictory. But then you wouldn't have learned about Mrs. Moffat's Shoo Fly Powders, so aren't you happy I adopted a narrower definition?
    – Kevin
    Commented Feb 13 at 6:16


This is not a comprehensive list, but here are some examples:

  • Lying while under oath is the crime of perjury (regardless of whether it causes harm)
  • States generally make it a crime to give false information to a law enforcement officer
  • Defamation per se is, by definition, a type of defamation that is actionable without proving damages. In most states, this includes things like false accusations of crimes or false accusations of sexual misconduct.
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    I don't think these examples are really on point. From the justice systems perspective, at least, perjury injures the justice system, and thereby the public at large. Just giving false information to police is not, as I understand it, typically illegal; instead, the lie must somehow interfere with police business, which would be a detriment.
    – bdb484
    Commented Feb 12 at 5:42
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    @bdb484 The OP's question isn't whether there needs to be harm, it's whether there needs to be demonstrated harm. So, taking your perjury example, perjury may well cause harm to the justice system, but it's still a valid answer if you can be convicted of perjury without having to demonstrate that harm.
    – JBentley
    Commented Feb 12 at 10:54
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    @JBentley - philosophically, could you hold that perjury always causes harm to the justice system? Because it harms a "public good" - the concept that the justice system is producing fair results?
    – lupe
    Commented Feb 12 at 12:06
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    @jackaidley Generally speaking, the US requires proof of harm in a defamation case, along with proof either that the defendant knew or should have known the statement to be false or that the victim is not a celebrity or politician and the defendant made the statement with negligent or reckless disregard for the truth or untruth of the statement. "Defamation per se" doen't need to clear either of those bars, and applies as SegNerd says only to a select few types of statements, usually claiming that somebody is a criminal or adulterer. In all defamation cases, truth is an absolute defense. Commented Feb 12 at 13:26
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    @stackoverblown As I said, the question isn't about whether it is or is not harmful. It's about whether it is a requirement in court that you demonstrate that it is harmful (see the OP's question and how it was worded). For example, if a prosecutor doesn't need to prove in court that you caused harm to convict you of a crime, then it is irrelevant whether there is actually harm or not.
    – JBentley
    Commented Feb 12 at 14:00


It is unlawful for a business to make statements in trade or commerce that: are misleading or deceptive; or are likely to mislead or deceive.

A lie is, by definition, misleading or deceptive but the prohibited conduct is broader than knowingly telling untruths (aka lying). Advertising puffery is excluded (e.g “Whiter than white”, “The best burgers in town”).

For a successful suit on a M&D claim, the plaintiff would need to demonstrate loss, but the conduct is also an offence. The government does not have to show that anyone was or might be harmed by the conduct; just that it happened. There is also no need to prove an intention to M&D, the conduct is sufficient.


There area number of specific lies that have been explicitly outlawed, without any need to show harm, even potential/future harm.

One prominent example is denial of the Holocaust, which is illegal in 19 countries.


"Lying per se is not illegal. For it to be so, the person lied to has to suffer a detriment that the lier [sic] ought to prevent"

That will not be correct. For example, I go to the lost and found and lie to them that I lost my iPhone, giving a precise description of the iPhone that someone else I know lost. The person lied to (the employee at the lost and found) will not suffer any detriment; the rightful owner will. Or any time to go to a shop and lie to an employee to defraud the store, the employee lied to is unlikely to suffer a detriment.

Now in court, if I lie and give a false alibi to someone who is absolutely innocent but cannot prove it, that's perjury. Even though nobody suffered (including the state who would have convicted an innocent person without my lie), it's still perjury.

  • The first two paragraphs of this answer don't seem to be an answer, nor do they seem necessary to support the part about perjury which does answer the question.
    – kaya3
    Commented Feb 13 at 22:54
  • @kaya3 What exactly does the first half of the question say as a suggested answer?
    – gnasher729
    Commented Feb 14 at 22:16
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    The question quotes that sentence but doesn't claim that it is correct, nor ask whether it is correct.
    – kaya3
    Commented Feb 14 at 22:20

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