So there are a few famous cases in the united states wherein booby traps were ruled to be illegal, as they're indiscriminate in their application.

Let's say we have material X. Material X is special, in that if someone applies harm with intent to hurt a human, and that harm is detected by Material X, it will instantly cause serious bodily harm towards the aggressor. Material X knows the intentions of the person, and will apply said harm accordingly. It is never wrong. Police and Firefighters acting with the intent to help people will never be hurt by Material X nor will innocent children, individuals, or animals. Material X only harms "bad guys".

To my understanding, material x is very discriminatory, and thus would be legal to booby trap my property with, no? For the sake of the question, we can assume we're in the state most lenient towards booby traps with regard to legislation, and that federal law is the focus here.

Is my understanding correct?

  • 4
    This looks like a question for work building SE… Aug 15, 2023 at 5:34
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    And how would the designers of Material X implement the axiom "One person's terrorist is another person's freedom fighter"? Aug 15, 2023 at 10:33
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    I don't understand the point of these questions. OP has laid out a hypothetical scenario and asked how the law applies to it. World Building has nothing to offer on this question.
    – bdb484
    Aug 15, 2023 at 12:53
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    @bdb484 Because the scenario that the OP is suggesting is so fantastical that it will never occur in the real world. It's like asking what is the role of customs and immigration laws in a world where everyone can fly like Superman. It's purely philosophical rumination.
    – Peter M
    Aug 15, 2023 at 12:58
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    A legal system anything like our own has no relevance to a world where objects can infallibly know a person's intent.
    – ohwilleke
    Aug 16, 2023 at 2:35

1 Answer 1


It would be prima facie setting a trap or causing bodily harm with a trap

The act of deploying Material X would be the offence of setting a trap likely to cause bodily harm. If Material X is triggered then it would also be the offence of causing bodily harm with a trap. See s. 247 Criminal Code.

Self defence or defence of another require that the illegal act be reasonable in the circumstances

For self-defence or defence-of-another to excuse or justify this act, one needs to satisfy the elements of s. 34 of the Criminal Code:

34 (1) A person is not guilty of an offence if

(a) they believe on reasonable grounds that force is being used against them or another person or that a threat of force is being made against them or another person;

(b) the act that constitutes the offence is committed for the purpose of defending or protecting themselves or the other person from that use or threat of force; and

(c) the act committed is reasonable in the circumstances.

(2) In determining whether the act committed is reasonable in the circumstances, the court shall consider the relevant circumstances of the person, the other parties and the act, including, but not limited to, the following factors:

(a) the nature of the force or threat;

(b) the extent to which the use of force was imminent and whether there were other means available to respond to the potential use of force;

(c) the person’s role in the incident;

(d) whether any party to the incident used or threatened to use a weapon;

(e) the size, age, gender and physical capabilities of the parties to the incident;

(f) the nature, duration and history of any relationship between the parties to the incident, including any prior use or threat of force and the nature of that force or threat;

(f.1) any history of interaction or communication between the parties to the incident;

(g) the nature and proportionality of the person’s response to the use or threat of force; and

(h) whether the act committed was in response to a use or threat of force that the person knew was lawful.

The Supreme Court has said (R. v. Khill, 2021 SCC 37):

it is for the trier of fact to assess and weigh the factors and determine whether or not the act was reasonable. This is a global, holistic exercise. No single factor is necessarily determinative of the outcome.

The use of Material X would not be reasonable in many circumstances

The fact that Material X will "instantly cause serious bodily harm towards the aggressor", triggered by any harm with intent, would in many circumstances take the use of Material X outside of what would be found to be a reasonable act in self-defence or defence of another.

  • I tagged this as united states, but this canadian law perspective is very interesting, and provides some relevant insight, I think.,
    – tuskiomi
    Aug 15, 2023 at 19:21
  • You missed that what is reasonable of the circumstances requires knowledge of the actual circumstances - it’s impossible to know them in advance.
    – Dale M
    Aug 15, 2023 at 21:35

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