Hypothetically speaking, let's say that a person is very paranoid about intruders, government, end of the world, so on. They decided to buy some land and have a fence around the property with clear markings "do not enter" and warnings that there are "traps" in the area. The person makes every reasonable attempt to warn people not to enter.

Now after sometime, authorities secure a search warrant and approval to raid the house via legal means, and the warrant and raid are both justifiably issued. Let's assume that the person was willing to cooperate with the authorities as well after they had identified themselves. The person is also willing to assist in disarming / identifying any traps.

Would the home owner be liable for any damages done to the authorities if they were injured by his "traps" prior to them identifying themselves or after?

Note: Trap could be anything in FM 5 31 maybe even an inner electric fence.


2 Answers 2


Even if the authorities aren't injured, the homeowner may well face criminal charges. Many states make it illegal to set booby traps; for instance, California makes it a felony in section 20110 of the Penal Code. The definition of "boobytrap" in the code is "any concealed or camouflaged device designed to cause great bodily injury when triggered by an action of any unsuspecting person coming across the device;" on the face of it, it is definitely not clear that a generic "there are traps" sign makes it not a boobytrap (whereas a sign on the trap announcing its presence probably would).

If a trespasser falls victim to a trap, that can be grounds for a successful lawsuit against the homeowner; see Katko v. Briney (an Iowa civil case). The duty of care to trespassers is low; there's no general duty to mitigate hazards. However, one part of the duty is generally that one may not lay a trap for trespassers (example: report from Connecticut Office of Legal Research).

  • "designed to cause great bodily injury" - what about traps designed to incapacitate but not injure people? (say, by dropping them into a pit lined with soft material) Commented Oct 15, 2015 at 6:11

Unequivocally yes; the home owner would potentially be liable for damages and possibly with the crimes of grievous bodily harm and/or manslaughter.

Specifics will vary by state jurisdiction but the general common law remedy would be the tort of negligence. One of the recognised duties of care is of a occupier to entrants. Entrants include those with express permission (e.g. guests), by implied permission (e.g. the postman) and even in some circumstances uninvited visitors (especially children and "innocent" trespassers). An "innocent" trespasser is a person on property without express permission but who has not a) broken in and b) been asked to leave.

The law enforcement officers in the circumstances you describe, where the person is cooperative, would fall into the first category. Even without permission, they would probably fall into the second category and certainly the third if they were engaged in the lawful course of their duties. The validity of the warrant is irrelevant; if the officers genuinely believe that it is valid then they are acting lawfully. They could also enter lawfully if they had probable cause.

Having established that the duty exists, the occupier must take reasonable care not to cause injury to visitors. "Reasonable" is an objective measure and takes account of the circumstances, for example:

  • if the land is used as a military live firing range where the "traps" consist of unexploded ordinance, then erecting a barbed wire fence 6 foot high with signs in the most commonly used languages for the area is probably reasonable

  • if the land is used for hunting and signposted as such and the traps are for wild animals, are deployed only for the period of the hunting and signposted at the location then that is probably reasonable.

  • if the land is a private home then prima facie, booby-trapping it with the intent to injure or kill people is not reasonable and erecting signs does not make it so. In these circumstances the action is not just negligent, it is criminally negligent and any injuries or deaths caused would be criminal as well as open to civil remedies.

The Castle Doctrine is inapplicable see this section.

  • From what I found, there's no negligence-related duty towards trespassers in the US. The sole duty is that you can't purposely make it more dangerous for them (although traps would still be illegal).
    – cpast
    Commented Jul 24, 2015 at 0:58
  • 1
    @cpast That is my understanding in most common law jurisdictions, but there is a distinction between "trespass" and "innocent trespass"; the latter involves, for example, a person erroneously entering a property in the belief that it was another property - a duty is owed to these people.
    – Dale M
    Commented Jul 24, 2015 at 1:53
  • You might want to clarify that in the answer; I wasn't sure what "innocent trespasser" meant.
    – cpast
    Commented Jul 24, 2015 at 1:56

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