From the Wikipedia page on the trolley problem:

There is a runaway trolley barreling down the railway tracks. Ahead, on the tracks, there are five people tied up and unable to move. The trolley is headed straight for them. You are standing some distance off in the train yard, next to a lever. If you pull this lever, the trolley will switch to a different set of tracks. However, you notice that there is one person on the side track. You have two options: (1) Do nothing, and the trolley kills the five people on the main track. (2) Pull the lever, diverting the trolley onto the side track where it will kill one person.

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What are the legal aspects of finding yourself in a train yard in the United States when this happens? Is it a crime to pull the lever? Is it a crime to not pull the lever? Does it depend on if you're professionally qualified to pull the lever?

  • Note that the situation is highly artificial both in the assumed omniscience (there will be n1 vs. n2 deaths) and in the assumed dichotomy of options. How about: since you are anyways (almost) omniscient and able to act correctly under great stress, you pull the lever at exactly the right time to derail the trolley. Or, you pull the other lever that puts in the safety derail. Or, you get scared stiff and are anyways unable to do anything. As soon as you are able again to act, you call rescue. Commented Aug 4, 2020 at 9:44

3 Answers 3


Doing nothing is legally safer than doing something, but you're not without hope if you pull the lever. Although you'll likely have committed murder or at least manslaughter, case law is littered with lenience in exigent circumstances, even where convictions have been affirmed.

Because this is a philosophical problem, there are plenty of opinions from that perspective, but not so many from a legal standpoint.

Let's assume that you're an innocent bystander, (not an employee of the railway company or the train company, etc) and have no duty to act.

If you do nothing, then it is unlikely that you would be charged with a crime - you had no duty to fulfill, and therefore not negligent. There's little doubt that not pulling the lever is the safer option.

More interesting is when you choose to pull the lever - then it's probable that you would have charges of murder, or at least manslaughter, brought against you by the state. What defenses does the law offer?

Let's assume that you are aware that pulling the lever will kill a person.

The primary defence is a legal principle of necessity: where your criminal actions are not protected or excluded by some other statute or principle, the fact that you were obliged to take this action in order to prevent some greater harm may safeguard you from penalties.

There are certain elements of necessity:

  1. That you did not create the danger that caused you to commit the crime;
  2. That you ceased the criminal activity as soon as practicably possible;
  3. That you had no reasonable alternative; and
  4. The harm that you prevented was greater than the harm that you caused.

I see such a defense only possibly falling over on (4), where the prevented and caused harm, in the case of human lives, are inherently very subjective.

Unfortunately, each state has different rulings regarding the threshold for evidence of this defense.

One of the most famous cases where necessity was attempted as a defense to murder, with remarkable parallels to this hypothetical, is that of R v Dudley and Stephens:

  • A crew of four found themselves on a lifeboat at sea with no food and no water, and with no prospect of rescue.
  • One of them was a child (Parker) and was nearing death and unconscious.
  • Two of them (Dudley and Stephens), after some discussion over drawing lots, decided that the child would be killed before his natural death, in order that his blood be better preserved for drinking.
    The last crew member, Brooks, was silent on the matter.
  • After killing Parker, Dudley, Stephens and Brooks fed on Parker's body.
  • During the trial, the matter of necessity as a defense to murder was considered.
  • The judges found that there was no common law defence of necessity to murder, and Dudley and Stephens were sentenced to death with a recommendation for mercy.
  • The Home Secretary commuted their sentences to six months' imprisonment.

This case concerns essentially the choice you're making in the trolley problem: either the four crew members were going to die, or one of them would definitely die and the others might live. It's easy to say that they should have just waited, but they didn't have the benefit of hindsight.

It's also a great example of a situation where although the law says one thing, it doesn't align with our morals and ethics, and while it's a UK case, I would wager that almost every lawyer in common law countries would have heard about it.

  • 1
    Note: in some (most? all?) states, intentional homicide can never be justified under necessity.
    – cpast
    Commented Aug 5, 2015 at 3:06
  • @cpast I'm aware that necessity isn't a defense to murder, but even manslaughter? Also, do you mean intentional as "deliberate" or "premeditated"?
    – jimsug
    Commented Aug 5, 2015 at 3:15
  • @jimsung I think manslaughter is state-by-state, but I'm not so sure throwing the switch would be manslaughter. "Intentional" means "some actual statutes say 'intentional,'" but I think they mean "deliberate" (i.e. murder)
    – cpast
    Commented Aug 5, 2015 at 3:21
  • 4
    Interesting. I mean, clearly law and ethics aren't always on the same page. For instance, consider R v Dudley and Stephens - the accused were convicted and sentenced to death, in spite of their necessity defence; their sentences were commuted. Similarly in U.S. v Holmes, the court substituted manslaughter for murder as a result of a defence that included necessity.
    – jimsug
    Commented Aug 5, 2015 at 4:23
  • 1
    The R v Dudley and Stephens is very interesting and relevant. You should add a brief a description to the answer or at least a wiki link. I'll propose an edit at some point but I need to eat and get some other stuff done so you might beat me to it. Commented Aug 7, 2015 at 2:20

A perspective for the Czech Republic:

You are probably safe either way.

If you don't pull the lever, you might be guilty of Failure to provide help, but that requires you to be able to "provide help without any danger for self or another". Clearly, helping here endangers somebody, so you are not required to help.

If you pull the lever, you might be guilty of Murder, but the qualifications for dire need state that: If you commit a crime in order to prevent a danger, you are not guilty as long as you didn't cause a harm of the same magnitude or greater than the one you prevented. Regardless of philosophical discussions, I believe the law considers the death of multiple persons a worse outcome than the death of a single person (we can infer this from the fact that a more serious penalty is prescribed for a man who kills two people simultaneously than for a man who kills only a single person). Because pulling the lever kills one and prevents the death of five, you are causing lesser harm than would have occurred initially.

It doesn't matter whether you're professionally qualified to pull the lever. What might matter is whether you knew what pulling the lever would cause as you pulled it.

  • the law clearly considers the death of multiple persons a worse outcome than the death of a single person I would query this assertion. I'm not aware of any criminal system where someone can be convicted of multi-murder, rather than X acts/counts of murder. Although the outcome might be the same, the premise for your assertion just doesn't exist in the latter case. I could be wrong, though.
    – jimsug
    Commented Aug 10, 2015 at 6:58
  • 2
    Behold the Czech penal code: "Murder. (1) Who kills another person [...] will be punished by ten to eighteen years in prison. [...]" and "(3a) By imprisonment for fifteen to twenty years shall be punished whoever commits the crime described in (1) or (2) on two or more persons." The killing of multiple persons is a single crime, albeit a more serious one. Commented Aug 10, 2015 at 19:04
  • 2
    Wait, so if you kill three people your total sentence is less than that of three people who killed one person each? That makes it seem a lot like multiple lives are less valued.
    – jimsug
    Commented Aug 10, 2015 at 20:24
  • 1
    There's a range and other factors are taken into consideration. But you're right that the inference that multiple lives are more valued is not clear. I'll reword my answer. Commented Aug 11, 2015 at 8:09


You're better off from a legal perspective to do nothing.


My answer is solely based on this Wikipedia article I found.

Which says:

The details of good Samaritan laws/acts vary by jurisdiction, including who is protected from liability and under what circumstances.[23] Not all jurisdictions provide protection to laypersons, instead protecting only trained personnel, such as doctors or nurses and perhaps also emergency services personnel such as trained police, fire and EMS workers.

Common features: In some jurisdictions, unless a caretaker relationship (such as a parent-child or doctor-patient relationship) exists prior to the illness or injury, or the "good Samaritan" is responsible for the existence of the illness or injury, no person is required to give aid of any sort to a victim.


Ethics, morality and law usually comport. But not always.

I think you have successfully recognized a scenario in which the law, if followed to the letter, results in a suboptimal moral outcome. Maybe one could argue one life is just as valuable as five? But, theoretically, the scenario could have been constructed to make the comparison between one life and five thousand. Or five million. And instead of a person, it could be property that would get destroyed given the action choice versus one or more lives lost given the non-action choice. Thus making a clearer distinction between the better moral outcome.

The law is not set up to handle these individual "loophole" scenarios. So it should be no surprise to find many hypothetical examples one can construct to illustrate this.

By way of comparison, Judaic law is practiced in the U.S. The conclusion under that legal system is the same. As this Stack Exchange question and answers point out.


I'm not a lawyer. So if you have a real situation you need help with, please hire a real lawyer and don't follow my advice or any advice from strangers on the internet.

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