My understanding is that many easily-concealed weapons are illegal to use for self-defense in many if not most states. For example, knuckle-dusters are illegal to use in self-defense in most if not all of the country. What I do not understand is how the courts tend to define weapons. Is there a legal difference between the following two scenarios?

  1. A young woman leaves her martial arts practice, carrying a fighting stick which she bought online specifically for that martial art. She is attacked in the parking lot and uses the stick in self defense.

  2. A young man is out running when someone jumps him from behind a bush. He manages to grab a heavy stick which is on the ground nearby, likely broken off a nearby tree in a recent storm. He uses that stick to fight off his assailant.

I can imagine similar analogues for other weapons. For example, knuckledusters:

  1. A mechanic buys a pair of knuckledusters and carries them in his trendy fanny pack every day to and from work. One day he is attacked by a gang-member. He defends himself with his knuckledusters, and seriously injures his assailant.

  2. A locksmith is walking to work when he is attacked by a gang-member. He happens to have a bunch of keys in his hand. He slips his index finger through the key-ring, turning the keys effectively into a spiked knuckleduster, and uses it as a weapon in self defense, seriously injuring his assailant.

I hope my point makes sense. While these scenarios may seem far-fetched, I imagine that people probably frequently use whatever they happen to have on hand as a weapon when attacked, if they resist at all. So in general, I'd like to know how the courts in the US tend to treat those sorts of situations, and where the line is drawn between weapons and tools or objects which coincidentally happen to be useful as weapons.

Examples of items which could coincidentally be useful as weapons could include key-rings, heavy metal flashlights, metal "tactical" pens, certain EDC tools such as this, umbrellas, heavy Stanley mugs, etc. Their real-world weapon analogues, respectively, could be knuckle-dusters, metal whap-sticks, metal spikes, knuckledusters again, fighting sticks, and clubs.

3 Answers 3


Illegal weapons

Weapons are defined and are made illegal by statute. In many states, it is illegal to possess brass knuckles. For example, California penal code 12020(a)(1) makes it illegal to possess "any metal knuckles", "writing pen knife", "any leaded cane", among other things. I don't know of any state where it is illegal to pick up a stick, or keys, etc.

So, yes, there is a legal distinction between your four scenarios. The mechanic is committing a crime by merely possessing the brass knuckles. The others are not committing a crime by the mere possession of the things you mention (unless there are states where they've been made illegal).

Effect on a self-defense analysis

Courts would have the jury go through the same self-defense analysis in each of these cases, regardless of the legality of the weapon used. We've described that analysis here. A pure self-defense analysis does not factor in the legality of the weapon that is used. But, if the weapon has been made illegal because of its disproportionate ability to injure, etc. that might weigh against the reasonableness of the force that was used when choosing to use that weapon in self-defense. Possession of an illegal weapon might also weigh against the credibility of the owner of that illegal weapon.

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    Further to your last statement: Possession of an illegal weapon might also give weight to suggestions that a defendant was "looking for trouble" or "disposed to use unreasonable force."
    – feetwet
    Commented Feb 24, 2017 at 2:28
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    Thanks for this, great answer. Also the answer you linked to was very informative. I appreciate your clear and simple explanation, without the sort of legal verbosity which would likely go right over my head :) Commented Feb 24, 2017 at 5:37

Usually self-defense laws govern when deadly force, or proportionate non-deadly force may be used, without regard to the tool used to inflict that force (although sometimes firearms are presumed to be deadly force if fired). This doesn't hinge directly on the legality of the weapon.

One may be not guilty of a crime that is excused by an appropriate use of force in self-defense (e.g. assault or murder), while still being guilty of possession of an illegal weapon, even if that illegal weapon was used appropriate for self-defense purposes.


I just came across the illuminating decision by the New Jersey Supreme Court in Montalvo v. State. (Of course this is only law in New Jersey, but NJ is known as one of the more anti-weapon states in the U.S., and the decision does reference the SCOTUS decision in District of Columbia v. Heller.)

The ruling maintains that outside of the home the elements of the crime of Unlawful Possession of a Weapon (N.J.S.A. 2C:39-5(d)) apply. In relevant part, the Model Jury Charge for that crime provides:

In order to convict the defendant [under N.J.S.A. 2C:39-5(d)], the State must prove the following elements beyond a reasonable doubt

  1. That the item in question is a weapon (or that there was a weapon);
  2. That the defendant possessed the weapon knowingly; and
  3. That the defendant’s possession of the weapon was under circumstances not manifestly appropriate for a lawful use.

The third element that the State must prove beyond a reasonable doubt is that the defendant possessed [the item in question] under circumstances not manifestly appropriate for such lawful uses as it may have. It is not necessary for the State to prove that the defendant formed an intent to use [the item] as a weapon. It is, however, necessary for the State to prove that it was possessed under such circumstances that a reasonable person would recognize that it was likely to be used as a weapon; in other words, under circumstances where it posed . . . a likely threat of harm to others and/or a likely threat of damage to property. You may consider factors such as the surrounding circumstances; size, shape and condition of the object, the nature of its concealment, the time, place and actions of the defendant when it was found in his possession to determine whether or not the object was manifestly appropriate for its lawful use.

The jury in the original case asked for clarification on whether "self defense is a lawful use of a weapon." Referencing State v. Kelly, 118 N.J. 370 (1990), the court stated:

This statute is 2C:39-5(d). Section 5(d) prohibits the possession of implements as weapons even if possessed for precautionary purposes, except in situations of immediate and imminent danger. Although self[-]defense involves a lawful use of a weapon, it does not justify the unlawful possession of the weapon under Section 5(d) except when a person uses a weapon after arming himself or herself spontaneously to repel an immediate danger. Obviously, there may be circumstances in which a weapon is seized in response to an immediate danger, but ensuing circumstances render its use unnecessary. Under such conditions, the individual may take immediate possession of the weapon out of necessity rather than self[- ]defense. However, it would appear that the availability of necessity as a justification for the immediate possession of a weapon, as with self[-]defense, is limited only to cases of spontaneous and compelling danger.

I.e., as best I can tell, if you find yourself in "spontaneous" danger and can in the moment acquire a weapon appropriate to defend against the danger, then you cannot be found guilty of criminal possession of a weapon. Otherwise, your possession of an item that can be used as a weapon is subject to the "intent" test described in the jury instructions.

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    Wow! Thank you very much, this was an exceedingly interesting (and frankly surprising) bit of information. Commented Jul 25, 2017 at 1:48

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