I've been studying the relation between free will and the U.S. criminal justice system, and it appears that there is the argument that whether or not a defendant had free will to commit a crime is a significant factor in determining whether or not the defendant is factually guilty of having committed a crime.

A "universal and persistent" foundation stone in our system of law, and particularly in our approach to punishment, sentencing, and incarceration, is the "belief in freedom of the human will and a consequent ability and duty of the normal individual to choose between good and evil."

From a website of Attorney John Guidry,

Free will creates the moral structure that provides the foundation for our criminal justice system. Without it, most punishments in place today must be eliminated completely.

However, it does not appear to be published much in legal literature of legal cases. From what I have studied, the legal system adheres to the philosophy that criminals commit crimes via compatibilist free will. This, however, is from what I have pieced together from legal literature that I have read over the past 10 years. It seems to be a tenet that comes from the neo-classical school of criminology.

I have yet to read some kind of Federal or State source that argues that compatibilist free will is presumed to be had by anyone who commits a crime. For instance, I might construe the appeal of Grayson v. United States to not touch upon findings of guilt but instead punishment, sentencing, and incarceration (as if whether or not a defendant had free will influences those aspects of a criminal case rather than influences a finding of criminal guilt).

Where in U.S. law is it officially argued that the U.S. criminal justice system presumes defendants commit crimes with free will?

  • 5
    As an interested amateur about legal issues, I would think that without the assumption of free will, issues of punishment... incarceration, fines, probation... would be hard to make rational. Similar to "not guilty by reason of insanity", which one could argue could apply to anyone who does anything (by convention) anti-social? Jul 17, 2023 at 17:32
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    @paulgarrett I think you could also rationally make the case that even if free will doesnt actually exist, it is at very least a convincing illusion that effectively still governs our actions, even if ultimately we are less free than we feel. In that case, punishment would also not be a choice anyways, but the illusion of choosing to punish is as real as the illusion of choosing to do something illegal. It would all come out the same basically.
    – JMac
    Jul 18, 2023 at 11:36
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    Isn't this what the insanity defense is based on? If you are (proven to be) not of sound mind then you cannot be punished for your acts. Jul 18, 2023 at 13:17
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    "Where in U.S. law is it officially argued...": Why should it be "officially" argued anywhere? Principles considered obvious, or common knowledge, normally don't get discussed explicitly. The role of a judge is to resolve a case in front of them, not to explore abstract philosophy. Even if a defendant were to try to use a defense based on not having free will, I would expect a judge, rather than deeply exploring the issue or giving citations, to simply say "denied as frivolous" and move on. Jul 18, 2023 at 20:21
  • @NateEldredge: When physics or other hard science makes advances, we generally ask the law to respect it. For example, it would be quite interesting if there were legal writing about the Free Will Theorem, a concrete and well-evidenced statement about compatibilist free will and physics.
    – Corbin
    Jul 19, 2023 at 17:27

7 Answers 7


It is an unquestioned pre-American axiom, expressed in Latin as actus reus non facit reum nisi mens sit rea ("the act is not culpable unless the mind is guilty") which has been part of the Anglo-American legal system since at least the 17th century. It is thus presupposed in all criminal proceedings. It's not that a person only commits a crime with free will, it's that it is not deemed to be a crime if there is no free will. A person can be held at gunpoint and required to commit a criminal act: the person does indeed have free will to choose to be killed rather than commit the act, but the act is legally excused since dying is never held to be the only acceptable alternative to committing an otherwise-criminal act.

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    – Dale M
    Jul 17, 2023 at 20:36
  • @user6726 I am still skeptical of your answer. From what I've read, free will came about from the Stoics. And for what I've read of ancient greco-roman law, there wasn't a belief in free will. Instead, they used some concept of responsibility that was independent of a requirement of free will: I can't find the source for this, though. At earliest, it appears the matter of "free will" can be related to Blackstone's view of a "vicious will" being required. I suggest you provide a source, something that can verify your answer. Jul 24, 2023 at 20:20

I don't see how any legal system, US,or otherwise, could work without the assumption of free will.

  • Defendant: I don't have free will, so I can't be held responsible for my actions.
  • Judge: I don't have free will either, so I'm going to have to sentence you.
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    This is also how I've always seen it. It's essentially a moot point when you think it through. The question of freedom in specific situations is still relevant, but not overall human freewill.
    – JMac
    Jul 18, 2023 at 11:49

Conduct that is involuntary (in the sense of having no conscious control or awareness of one's actions) "cannot be criminal" (R. v. Brown, 2022 SCC 18):

To deprive a person of their liberty for that involuntary conduct committed in a state akin to automatism — conduct that cannot be criminal — violates the principles of fundamental justice in a system of criminal justice based on personal responsibility for one’s actions.

  • Interesting answer. You could improve it by providing a summary of the facts in the case in order to give context to the quote.
    – David42
    Jul 18, 2023 at 14:42
  • Involuntary acts do not relate to the philosophical concept of free will. You can have conscious control and awareness without having free will, if your consciousness is driven fully by external forces (biology and environment).
    – NotThatGuy
    Jul 18, 2023 at 15:18
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    @NotThatGuy involuntary literally means, by etymologie, "without will". You can't do something voluntary without having a will, by definition, and it has to be free to be your own, otherwise who is on trial?
    – njzk2
    Jul 19, 2023 at 21:10
  • @njzk2 Having will doesn't mean having "free" will. You didn't seem to have risen any objection to "if your consciousness is driven fully by external forces" (which is the issue at hand), but rather you seem interested in playing semantic games (while seemingly not knowing anything about the relevant philosophy). Note that I am taking an incompatibilist view here.
    – NotThatGuy
    Jul 20, 2023 at 8:00
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    @NotThatGuy if those are external forces, do you have a will? is it yours really?
    – njzk2
    Jul 20, 2023 at 19:55

I found the following in State v. Vinson, 269 Wis. 305 - Wis: Supreme Court 1955:

The instruction of which appellant complains does no more than inform the jury of the well-known rule that one is presumed to intend the natural and reasonable consequences of his acts but that the presumption may be rebutted.
"... there are certain presumptions which react against accused, such as the presumption of sanity, considered below in sec. 584, of knowledge of the law, see infra sec. 586, and that a person intends the natural and reasonable consequences of his acts, ..." 22 C. J. S., Criminal Law, p. 893, sec. 579.

I don't know that it's possible to intend to do something without free will, so I think these presumptions also imply a presumption of free will.

The citation to a law encyclopedia would seem to indicate that these presumptions come from common law, and not from any particular statute (if the presumptions came from statute, they'd cite the statute instead.)

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    Reminds me of the Caillaux scandal. "My husband's unmanly non-defense of my honor drove me to insane state of woman acting as man, whereby I shot Calmette (which is what my husband should have done)".
    – RonJohn
    Jul 18, 2023 at 13:56
  • Intent equals will, roughly speaking. If your intent/will is fully determined by your biology and environment, one could argue that it's not "free" (that's an incompatibilist view).
    – NotThatGuy
    Jul 18, 2023 at 15:46

I may be wrong, but it sounds like the question is flawed in that it makes inaccurate assumptions... namely; our legal system specifically addresses free will. It does not.

To operate effectively we assume a person cannot be found guilty of committing a crime unless they did so with the ability to make a choice.

From a recent ruling:


from page 3, paragraph 1

Defining the precise relationship between criminal culpability and mental illness requires balancing complex considerations, among them the workings of the brain, the purposes of criminal law, and the ideas of free will and responsibility. This balance should remain open to revision as new medical knowledge emerges and societal norms evolve.

Seems pretty clear they address the question you ask here?


Even if we were like machines or primitive animals, just reacting to the input we get in a deterministic fashion, the justice system still makes sense.

It is clear that punishment has effect, and that people like to avoid punishment, no matter whether this a free choice or just wired into our brain.

So I see no reason why Free Will is a necessary assumption.

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    Punishment has doubtful efficacy as a deterrent for crime (and that's coming from the US Department of Justice). There are a few possible (not necessarily good) reasons to send someone to prison: 1) as a deterrent (mentioned above), 2) as a punishment for being a "bad person", 3) to prevent them from causing future harm, 4) to make victims or their families, or society in general, feel better. #2 would be irrelevant if free will doesn't exist.
    – NotThatGuy
    Jul 18, 2023 at 15:44
  • Wow. Common sense is authorized. We are living through proof this document is... flawed.
    – STS1SS
    Jul 19, 2023 at 18:38

After some reflection, I have theorized that where it is "officially" stated that the American criminal justice system presumes that defendants commit crimes with free will is found in the U.S. Constitution: To clarify, a necessary component of something being a crime (in the U.S.) is that the alleged crime was done with free will. More specifically, the official stating of such is found in the due process clauses of the U.S. Constitution, namely the Fifth and Fourteenth Amendments.

My reasoning for this is derived from the U.S. Constitution's Supremacy Clause:

"This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding."

As such, if there is something to be learned about how the American legal system works, it should be able to be derived from the U.S. Constitution. Although the Fifth and Fourteenth Amendments do not explicitly detail how free will is presumed to exist within those who have committed a crime in the land of the U.S., case law [such as United States v. Grayson 438 U.S. 41 (1978)] explicates this matter. Furthermore, common law tradition of free will being a component of a crime having been committed is codified in the Fifth and Fourteenth Amendments rather than explicitly argued.

So, two things:

  1. As part of guaranteeing due process, it's required that for something to qualify as a crime, it must have been committed via free will. (It's not fair to consider otherwise)
  2. As part of due process, it is presumed that all persons have free will.

Answer: The Fifth and Fourteenth Amendments of the U.S. Constitution.

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