I own a few acres (in the USA) and want to put up a joke sign that says "Active Minefield". A friend mentioned that is illegal. I am not so sure, ergo looking for opinion or references.

I understand classic free speech examples like you can not yell "Fire" in a movie theater. Since this sign is on private land and will only be visible when you are on the property, I would love to have a legal opinion.

My alternative is to put up a sign "Keep Out: Testing Lasers from Space" which is a derivative of this idea and (IMO) would be considered humor. I know there is a line, how and where is that "line" defined?

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    You can put up a sign that is true, for example "Warning! This field is infested with an outbreak of creeping fescue". Or "Warning. Radiactive radon gas is present in this field." Apr 28, 2022 at 22:02
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    Don't do it in Laos or the Falklands or Kosovo... those guys have no sense of humor... Apr 29, 2022 at 0:51
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    Trespassers will be shot. Survivors will be shot again. ... "with respect to your own property, so long as you haven't agreed to any limitations on the appearance of your home (such as through a Homeowners Association or deed restriction), you're free to put up any signs you want, regardless of how violent, offensive, or profane they may be to others. That's the First Amendment at work — it limits the government's ability to regulate speech — so yes, a sign threatening to shoot trespassers is perfectly legal." huffpost.com/entry/does-posting-trespassers_b_7889192
    – Mazura
    Apr 29, 2022 at 2:14
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    Regardless of legal issues, this is a spectacularly bad idea in case emergency services ever need to come to your property.
    – gerrit
    Apr 29, 2022 at 7:52
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    I'd strongly argue from a moral perspective not to put anything on such a sign that might make someone think an identical sign elsewhere is also a joke when it isn't. If you're going to joke, it should be obvious to everyone regardless of context. For that reason, your alternative is much better. My personal favorite though is "No Trespassing: Prosecutors Will Be Violated"
    – T.E.D.
    Apr 29, 2022 at 15:44

3 Answers 3


At the federal level, 18 USC 35 is as close as you can get:

(a) Whoever imparts or conveys or causes to be imparted or conveyed false information, knowing the information to be false, concerning an attempt or alleged attempt being made or to be made, to do any act which would be a crime prohibited by this chapter or chapter 97 or chapter 111 of this title shall be subject to a civil penalty of not more than $1,000 which shall be recoverable in a civil action brought in the name of the United States.

However, the false information has to have a specific character. Ch. 97 regards trains and mass transportation systems (entering to commit a crime, terrorist attacks). I assume you don't have railroad lines running through your property. Ch. 111 regards shipping, presumably not relevant to your land. Finally, Ch. 2 ("this chapter") regards aircraft and motor vehicles: 18 USC 33 prohibits endangering... so for the sake of discussion, perhaps there is a false threat against motor vehicles (assuming there is a highway near your property). So...

(a) Whoever willfully, with intent to endanger...causes to be placed any explosive...in proximity to, any motor vehicle...

is a criminal. Therefore conveying false information that an explosive is in proximity to a motor vehicle is also against the law. That's probably close enough to warrant hiring an attorney before you end up arrested on a federal charge.

Para. (a) makes this action a matter for a civil penalty ($1,000 limit), whereas para. (b) of §35 makes it a crime if you act "willfully and maliciously, or with reckless disregard for the safety of human life". You joke would not rise to the level of willful and malicious, but it could easily be found to be negligent, so you could get a civil penalty.

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    Very cool work. See my other comment below for a little context, but this is the legal thinking I was interested in (as well as conceptual). This joke idea stems from my grandfather in NYC who had a notice on his car to keep it form getting towed. This is not a joke, it said "Sparkplug attached to gas tank, any attempt to move will cause it to explode". That was a loooong time ago. Thanks/accepted.
    – Marc
    Apr 28, 2022 at 23:01
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    Why "Therefore conveying false information that an explosive is in proximity to a motor vehicle is also against the law."? In essence, why lying about having committed a crime is itself a crime?
    – Greendrake
    Apr 28, 2022 at 23:08
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    The standard political rationale is that false alarms waste public resources.
    – user6726
    Apr 29, 2022 at 0:12
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    @Greendrake, in this case, I suspect what we're seeing is an unexpected interaction between two laws.
    – Mark
    Apr 29, 2022 at 2:21
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    The sign could safely convey truthful, albeit ambiguous information - something like : "WARNING : AREA HAS NOT BEEN CHECKED FOR LANDMINES. NO TRESPASSING"
    – J...
    Apr 29, 2022 at 15:57

My alternative is to put up a sign "Keep Out: Testing Lasers from Space" which is a derivative of this idea and (IMO) would be considered humor. I know there is a line, how and where is that "line" defined?

This distinction captures the key point. If your sign stating "Active Mine Field" would, in the overall context, be understood as humor and not as a true statement of fact, it will be protected by the First Amendment.

If, however, someone is basically defrauded by a sign, because it appears to a reasonable person to be making a true statement of fact upon which a person reasonably relies to their detriment (or perhaps could reasonably rely to their detriment for criminal law purposes), then it is probably not protected.

For example, suppose that your "Active Minefield" sign causes the fire department, when responding to a wildfire next door to your property, to take the long way around your property or to call in the bomb squad at great expense. You could have civil liability as a result. Similarly, if the fire department refused to respond to a fire on your property due to such a sign, your insurance company might have a ground to deny your insurance claim for damages that a prompt fire department response could have prevented.

And @user6726 points out circumstances where there could be criminal liability, although there, as in the civil case, the First Amendment would require those criminal statutes to be employed in enough of a common sense fashion to only be invoked in cases where a reasonable person would believe the sign to be purporting to be a true statement of fact in the overall context of the situation, in order to withstand an "as applied" constitutional challenge to a facially valid statute.

So, a "space lasers" sign (at least as of 2022 when there are no such things) would probably not give rise to legal or civil liability, but an "Active Minefield" sign without something involved in the presentations to clearly indicate that it is a joke (or a fictional depiction for temporary theatrical purposes, for example) to a reasonable person, could result in civil or criminal liability.

Similarly, if the sign was very artistic and also had pictures of Bugs Bunny and Coyote chasing each other, and images of obviously fake "land mines", or if the sign were accompanied by a picture of cow turds everywhere that made clear that the "minefield" was a field full of excrement rather than high explosives, it wouldn't be actionable.

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    Well said. The sign would "protect" a wooded area, technically our leach field. As for visibility, you would need to be on the property and past various "no trespassing" signs to see my humor. Still, I generally agree and wanted to get a good legal sniff for this topic. Thanks.
    – Marc
    Apr 28, 2022 at 22:56

My understanding (IANAL) is that mines are legal but heavily regulated (to the point that they are de-facto illegal). If you pay all the fees, fill out all the forms, jump through all the hoops you can legally mine your property.

The law (as I understand it) requires you to clearly identify areas where mines are present (i.e., post those "Active Minefield" signs). It does not require you to not post areas where mines are not present.

Indeed, I suspect that many of those "mine fields" near the Korean DMZ (both sides) are not mined. The "defenders" know (or should know) which "mine fields" are really mined and which are not. The "attackers" can not be sure. This is in compliance with international law as long as all the "real mine fields" are adequately signed.

However, there are a variety of disadvantages. One that others have not mentioned is that an "Active Mine Field" sign might be primae facie evidence that you have a mine field. The government can quickly check its records and determine that if you have a mine field it is an illegal mine field. Let's take this to a judge and get a warrant. We will call in specialists and (extremely carefully) dig up every square inch of your property looking for those illegal mines.

Looks like you do not have any mines. Your property is a mess - not the government's problem. It is hard to imagine any legal irregularities escaping the extreme scrutiny that your search team put your property through. Here are a bunch of citations for the violations noted.

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    That is an interesting take on this particular topic. I am thinking I may just change the sign to "Keep Out: Hidden Bear Traps". Almost as bad...
    – Marc
    May 3, 2022 at 14:11
  • @Marc I would recommend "WARNING: GOVERNMENT AUDIT ZONE", "BUREAUCRATS MAY BE ARMED", "PAY YOUR TAXES", "WOULD YOU LIKE TO TALK ABOUT JESUS?", "EAT MORE VEGETABLES AND LESS MEAT". These signs will discourage trespassers without giving law enforcement prima facie evidence of a crime.
    – emory
    May 3, 2022 at 14:30
  • I would post this sign (compliancesigns.com/pd/…) as a joke. It says "US GOVERNMENT PROPERTY. NO TRESPASSING ... PROSECUTION ..."
    – emory
    May 3, 2022 at 19:18
  • This is also a good one compliancesigns.com/pd/…
    – emory
    May 3, 2022 at 19:24
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    Then make them each sign unique somehow (different colors?) so they form a system of landmarks. Then use the landmarks when cross-examining law enforcement. "So you entered the property approximately 50 yards from the RED 'The right of the people to be secure in their persons, houses, papers, and effects ...' sign"
    – emory
    May 5, 2022 at 11:39

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