In the US, most if not all states have some kind of law(s) in place that prohibit the carrying of knives in school zones. While most states define a knife as a weapon by edge length, I can not find any legal definition of what constitutes an edge or what constitutes a knife as a weapon in regards to school zones.

Many things that some people may call a knife are not weapons at all such as palette knives, butter knives, oyster knives, etc. Palette knives are even required school supplies for many schools that have an art program.

Then there are things that look like knives, like nail files, letter openers, etc., which are not called knives, have no cutting edge, but which I've heard of people getting in trouble for purely on the grounds that they "look like knives".

There are also many tools that have an edge sharp enough to potentially cut or stab but not things that people would call a knife, like keys, chisels, box openers, saws, screwdrivers, etc. Many of these tools are allowed on school property by maintenance personnel and are required class materials in certain courses like wood-working, and keys are literally carried by everyone who drives into or through a school zone.

Then there are also "blunted weapons". "Wall-hangers" are decorative swords, daggers, etc. that look like they could be real weapons, but are blunted for safety, and so have no effective cutting or stabbing edges. Similarly, a fencing rapier also looks like a full length sword, but has been blunted and is required equipment on school campuses that have fencing teams.

On top of all of this, a handful of states, such as Louisiana, don't even have edge length restrictions that differentiate a short-bladed "tool" from a long bladed "weapon".

So the question is: with all the ambiguity and exceptions, are there any rulings in place that would allow a reasonable person of at least average intelligence to determine what constitutes the crime, and if not, could knife restrictions in school zones be considered void for vagueness under the 14th Amendment?

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    Unless there is a ruling somewhere this is going to be opinion. Commented Dec 7, 2022 at 15:46
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    "Many things ... are not weapons at all" - That is not the way it works. Anything that is used as a weapon, or can be used as a weapon, can be a weapon. Box cutters were used to hijack the 911 aircraft. A butter knife in a kitchen and a pallet knife in a studio are reasonable, a sharpened chisel in a playground is not. A reasonable person of average intelligence would be expected to evaluate the appropriateness of the item in the context it is found and err on the side of caution (i.e. safety of innocents, not presumption of innocence).
    – Paul Smith
    Commented Dec 8, 2022 at 0:32
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    Reading your comments to other answers, you appear to be trying to establish if you have a legal right to be in breach of schools rules, in particular in how they apply to the possession of weapons in a school zone, without actually breaking the law. The answer is no. You have the choice not to enter school zones. Choosing to enter those zones means choosing to abide by the laws and rules of those zones.
    – Paul Smith
    Commented Dec 8, 2022 at 0:45
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    There have been various cases of students being suspended/expelled from school for bringing "weapons" like fingernail clippers files to school, but these generally result from administrators refusing to exercise any judgement whatsoever and interpreting zero-tolerance policies in the most extreme possible way to avoid any responsibility. Generally these are not the smartest people making these calls.
    – barbecue
    Commented Dec 8, 2022 at 16:22
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    @PaulSmith Please don't leave answers in comments. (Also, your analysis is incorrect. The question is about state laws, not school policies, though [at least for public schools] either one is unenforceable if it violates the U.S. Constitution. Schools are frequently sued [and frequently lose those lawsuits and are enjoined from enforcing the policies] when they have unconstitutional policies.)
    – reirab
    Commented Dec 8, 2022 at 21:13

3 Answers 3


School administrators have the right to try to express the law in seemingly simpler language, but they do not have the right to enforce their misstatements of the law. The law of Louisiana does not refer to knives at all

Carrying a firearm, or dangerous weapon as defined in R.S. 14:2, by a student or nonstudent on school property, at a school sponsored function, or in a firearm-free zone is unlawful...

"Dangerous weapon" is defined so that it "includes any gas, liquid or other substance or instrumentality, which, in the manner used, is calculated or likely to produce death or great bodily harm". The law does not exhaustively list the things that count as firearms or dangerous weapons, so every individual is held responsible for knowing what the courts have held to constitute "dangerous weapons". A novice interpretation (not relying on case law) might lead to the conclusion that a speargun is not a "dangerous weapon" (perhaps on the theory that it is used underwater to spear fish), but a reasonable interpretation of "dangerous weapon" suggests that it is a dangerous weapon because it can be used to kill a person. The same is true of a pencil, as well as a dog.

You can turn to this article for an example of the dangerous weapon status of a dog, a propos Louisiana v. Michels, where defendant was "armed with a dangerous weapon". That court recited previous case law to the effect that

"the dangerousness of the instrumentality because of its use is a factual question for the jury" State v. Munoz, 575 So.2d 848, 850

RX 14:3 also states that

The articles of this Code cannot be extended by analogy so as to create crimes not provided for herein; however, in order to promote justice and to effect the objects of the law, all of its provisions shall be given a genuine construction, according to the fair import of their words, taken in their usual sense, in connection with the context, and with reference to the purpose of the provision

which means that if faced with a novel application (dog, pencil, or speargun), the jury can decide based on "context and purpose", not just narrow words. The article points to a law review article by a lawyer involved in the 1942 codification of Louisiana criminal law that "the code was to be read as a civilian document, not a mere compilation of common law rules", thus the code is shorter and uses plain language.

The article then reviews a number of previous rulings on the scope of "dangerous weapon", starting with Louisiana v. Calvin where it was ruled that teeth and fists are not dangerous weapons, even though you can kill a person with your fists. It therefore turns out that a "dangerous weapon" must be an inanimate object, under Louisiana law.

A knife can be found to be a dangerous weapon, as reported in this opinion (deportation dependent on a prior criminal conviction for felony aggravated battery, specifically referring to R.S. 14.2(3) and deeming a knife to be a dangerous weapon). Since that conviction is no being appealed at the state level, details of the knife-usage are omitted, so all we know is that a knife was used.

Insofar as box cutters were the essential weapons that brought about the airplane hijackings on 9/11, it is not unreasonable to at least consider that they are within the scope of "dangerous weapon" (I would not, but that's a matter for the jury). A butter knife or especially a pencil cannot reasonably be deemed to be "dangerous weapons". But there doesn't seem to be any case law specifically addressing these objects. If a pencil were actually used as a weapon, perhaps the jury might find that a pencil (so used) was a dangerous weapon. However, the question is about a law forbidding the mere possession of a dangerous weapon, eliminating how it was actually used from the calculation.

It is extremely unlikely that I would get arrested for driving past a school with a screwdriver in my car.

  • Depends on the type of knife. In some states bowie knifes are declared weapons, in others it's the length of the blade in others it is the style...
    – Trish
    Commented Dec 7, 2022 at 21:55
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    @Trish This is true in most states, but Louisiana has in recent years repealed nearly all of those laws. It is now legal in most of Louisiana to carry and conceal any style of blade with the exception of a couple very specific city ordinances and weapon free zones... which is part of where my confusion originated because I no longer knew how to define a knife as a weapon with those laws now repealed.
    – Nosajimiki
    Commented Dec 7, 2022 at 22:17
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    "Since that conviction is no being appealed at the state level" I am assuming from the context of the second half of the sentence that "no" is a typo and it should read "now" but it could equally read "not".
    – MT0
    Commented Dec 8, 2022 at 8:24
  • "The law of Louisiana does not refer to knives at all" is way too sweeping of a statement. RS 17:416 says a lot about knives legis.la.gov/legis/law.aspx?d=81024
    – DavePhD
    Commented Dec 8, 2022 at 15:43

No. Normally schools or school districts will have definitions of their terms covered in student handbooks or rule books that are communicated to the public at request. I recall my schools having definitions of knives that included size or material restrictions of the blade. In U.S. law, a violation of a weapon law can occur regardless of the weapon's ability to inflict actual harm. For example, by law, realistic toy guns must have an orange "safety cap" over the muzzle to indicate the gun does not work. If one takes that cap off or uses the toy in a manner where the safety cap's purpose to alert people to the gun's fake nature is defeated (such as holding the gun under clothing so that you can only see the outline) will be a violation against the weapon law, since the law doesn't care if the weapon is actually functional but rather that it was reasonable for someone to assume the weapon was functional and threatening.

It is also the case that no right is absolute and the government may restrict a right to something based on a compelling government interest. As most schools in the U.S. are government run, the compelling interest in the safety of those who are by law in the government's care during the course of the school day out ways the public interest in a right to carry arms on school property. In the case of private schools, they are allowed to restrict what items are permissible on private school property the same as any other private property owner.

The list of impermissible items may not be practice to post on a general sign at the front of the property but most likely can be easily found when talking with an administrator.

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    The question is asking about actual laws, not school regulations. Commented Dec 7, 2022 at 16:22
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    It is an important distinction that carrying a toy gun with no red tip does not violate any laws unless you use it in a manner to threaten or coerce a person as if it were a real gun. So, having a concealed toy gun with no red tip for example does not violate concealed carry laws. My question here is a matter of carrying, not how it is used.
    – Nosajimiki
    Commented Dec 7, 2022 at 16:56
  • @Nosajimiki And my point is that actual functionality is not part of the test for the violation of the rule, so long as it's reasonable to assume that the rule is violated (As for your question RE: Fencing equipment, it is my limited understanding that the tips of rapiers are obviously dulled (the little round sphere covering the tip of the blade). More likely than not, the school will at least keep it's rapiers rather than let students bring that particular piece of equipment (though I've never seen public school sponsored fencing clubs, at least not at the grade school level.).
    – hszmv
    Commented Dec 7, 2022 at 17:04
  • @hszmv They are not uncommon at the high-school level. Even California has them, and they are one of the least permissive knife states.
    – Nosajimiki
    Commented Dec 7, 2022 at 17:09
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    "They would likely have all pertinent legal definitions in a condensed format" <- this is a dangerous assumption since school handbooks often present laws in very skewed and deceptive ways to try to minimize thier legal liability. Thier "condensed format" is usually a declaration of everything they can do and an omition of every they can not do, unless required to disclose that they can not do it, and a lot of stuff that they expect you to sign waivers for.
    – Nosajimiki
    Commented Dec 7, 2022 at 22:56

Absolutely not

The 14th Ammendment:

No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.

I'm not sure what here you think would protect you from arrest & incarceration for carrying a "knife" on school grounds. All the state has to do is give you due process. The vagueness doctrine is from both the 5th and 14th Ammendments, and no, calling something a knife isn't going to run afoul of it. You can convince a jury that it wasn't a knife if you're arrested for it. People are going to know what the government means when they say "no knives at school."

Rules at school are different from laws you can go to jail for. If you can show me someone arrested for a nail file I'll respond, but schools can tell you to not bring a nail file to school all day long.

While we're at it, constitutional rights don't exist in a vacuum. They must be interpreted with all other rights, including the "necessary and proper" things governments need to do to make a country work. All the constitutional rights that say that they "shall not be abridged" are abridged daily for numerous good reasons. Things just wouldn't work otherwise.

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    "due process of law" is not the part in question, it is the "equal protection of the laws". "Void for vagueness" means that a law is void if it is so vague that it makes equal protection of the laws impossible to regulate. For example, 127 N.J.L. vas voided in State v. Klapprott because "That the terms 'hatred,' 'abuse,' 'hostility,' are abstract and indefinite admits of no contradiction." Also, I'm asking about legal rights in a school zone, not school handbook policy, because carrying a weapon in a school zone is an actual crime.
    – Nosajimiki
    Commented Dec 7, 2022 at 22:42
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    I have in my pocket an object with a hinged blade 32 millimeters long. Depending on the local rules, it is sometimes considered a knife, and sometimes not. (And it's not always the length that's the determining factor -- sometimes it's the fact that I can press the edge against my thumb without cutting.)
    – Mark
    Commented Dec 8, 2022 at 3:48
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    @Nosajimiki, "knife" is hardly vague. Again, things like this are built to be decided by juries. Your right is to not carry a knife in a school. A person of reasonable intelligence knows what that means.
    – Tiger Guy
    Commented Dec 8, 2022 at 14:15
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    @TigerGuy "things like this are built to be decided by juries." Juries decide it yes, but part of the 14th Amendment is the guarantee that no law may be so vague that juries consistently come to different conclusions when all relevant factors are the same. Everyone has thier own ideas about at what point a knife is just a strip of metal. user6726's answer actually clarified the issue a lot since I was mistakenly led to believe that the "dangerous weapons" ban was a "knife" ban. Dangerous weapon laws set qualifiable thresholds that many knife laws do not.
    – Nosajimiki
    Commented Dec 8, 2022 at 15:05
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    Coming Up Next: Local school board bans use of blade servers to comply with weapons policy.
    – barbecue
    Commented Dec 8, 2022 at 16:09

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