Imagine a perfect legal system, whatever that looks like to you. I don't care what it is, just put it in your head.

There are plenty of examples of moral, legal action that can happen under this system, such as charity. There are also plenty of immoral, illegal actions, such as murder. Though not nearly as pervasive, there are a few immoral, legal actions, such as insulting someone in a way that qualifies as free speech.

However, I can't think of any moral actions that a perfect legal system would make illegal. The Overlap Thesis says no such examples could exist, but not everyone subscribes to that view.

Edit: An alternative way of asking the same question
Lets say Alice and Bob are having a conversation.

A - I think in a perfect legal system would have the law, "[action] is illegal".
B - Do you think it is moral to do [action] in [context]?
A - Yes.
B - So wouldn't a better legal system have the law, "[action] is illegal, unless it is done within [context]?"

Is there a combination of a moral outlook and desired legal system that allows Alice to answer 'No'?

  • It depends a lot on a definition for morality. For example, if I am worshipper of Kali-Ma and it is considered moral to follow one's god's command, it is therefore moral that I strangle strangers in honor of my god. But it is probably illegal, as not everyone worships Kali-ma.
    – armand
    May 28, 2021 at 4:27
  • If you believe you that it is moral to strangle people as worship, why would your idea of a just legal system not have an exception in its laws of murder for that type of worship?
    – E Tam
    May 28, 2021 at 4:30
  • It could be just for me and other Kali worshippers, but it would not be just for non worshippers who have no reason to condone strangulation for a God they don't believe in. A perfectly just society would certainly have to be seen as just by each of its citizens.
    – armand
    May 28, 2021 at 4:48
  • 2
    "A perfectly just society would certainly have to be seen as just by each of its citizens." No legal system can be seen as just according to each and every of its citizens unless all the citizens have the same legal positions. The ritualistic murderers want ritualistic murder to be legal; everyone else want ritualistic murder to be illegal. No matter what legal system you pick, one group has to not get what they want. Also, I am asking about a just legal system; whether that implies a just society is another matter altogether.
    – E Tam
    May 28, 2021 at 5:29
  • "Imagine a perfect legal system, whatever that looks like to you. I don't care what it is, just put it in your head." I'm just following your instructions here, man. I think it's part of the problem that you ask what would happen in a just legal system while at the same time overtly not caring enough to define what it would be. To me a perfect legal system would appear just to everyone. Otherwise, it's not perfect.
    – armand
    May 28, 2021 at 7:00

2 Answers 2


Of course, one answer is trivial--that if you don't make anything illegal, nothing that is moral is illegal. You can always make the laws lax enough to make sure that all moral actions are legal.

But let's assume you don't want the trivial answer; you want a legal system that makes immoral things illegal as well as moral things legal. There is no way to do this.

Let's consider speeding: speed limits are designed for safety, assuming certain traffic conditions, road conditions, atmospheric conditions, driver experience, and vehicle stability. Usually the speed limit is based on conditions that are somewhere between average and worst-case. But suppose the Super Bowl is on so there is no traffic, the road was just repaved, it's clear and sunny, you are young enough to have quick reactions but old enough to be a very experienced driver, and you are driving a new sports car. Then there is no way that going ten miles over the speed limit is creating any hazard for anyone, so doing so is not immoral, but it is still illegal.

You might argue that in this case, let's change the legal system to say that there is an implicit addition to the speed limit based on conditions. But this puts the judgment about speed back in the hands of the driver, and the whole point of the speed limit was that drivers cannot be trusted to make that judgement. The only alternative is to create a complex set of laws about the various kinds of conditions and how much each condition affects the posted speed limit.

Now, I don't think it would be possible to come up with a set of laws that accurately reflects reality as to how fast it is safe to go in all conditions, not least of all because "safe" is an imprecise word. But let's say you could, then surely this set of laws would be so complicated that most drivers could never remember them. Surely it is not just to demand that drivers obey laws that are too complex to remember.

But let's say that someone was able to come up with a miracle formula that is easy to remember, easy to calculate, and everyone can apply it. Now suppose you have a child in your car who is bleeding to death from an injury. Do you have to follow this formula, or does the very real and immediate danger to the child outweigh the speculative and statistical danger of speeding? Presumably you agree with me that it is moral to speed in this case (within reason). So now we need to add an entirely new dimension to our speeding laws to cover the level of urgency that the driver is facing. Is it only life and death situations? What about fear of losing a limb? What about fear of losing a finger? What about fear of losing a job? The possibilities are just too complex to ever encode into written law.

An objection you might make to this whole argument is that speeding is not really a law; it is a regulation, and the law can be written in such a way as to make it legal to violate regulations, so long as you can justify doing so. But then let's talk about stealing. When is it immoral to take something that doesn't belong to you? Can you reach into someone's car and grab a box of tissue when your child gets an injury and you need to stop the bleeding? If the child's life is in danger and you notice the keys are in the car, and you have no other way to get to an emergency room, is it OK to take the car? Is it OK to pick up a pretty rock that you find on someone else's property and keep it? Is it OK to take someone's cat when they have been neglecting it and abusing it for months?

The point is that morality--what is right and wrong--is just too complex an issue to ever be encoded into written laws.


There are degrees of illegal, and of moral. Moral decisions leave room for discouraging things without prohibiting them.

It might still be illegal to drive at twice the speed limit. And someone might morally violate that law if they are driving someone to the hospital. But you might not want a blanket list of exceptions built into the law, because people would take legalistic advantage. You might want to leave the option of just taking the ticket.

By accepting the ticket you are deciding that your action is ultimately moral, but that it is presuming upon judgement that might not be universally accepted, so you just agree to accept the punishment for that presumption. The citing officer or the judge might or might not mark it down, but you have accepted it is OK.

By deciding to endanger others to save someone, you are making this a 'trolley-problem' instance. There can be no overall agreement about that built into any legal system. Since we can't all agree, you are 'buying' the right to decide for yourself. If you really think your case is that clear, you can challenge the premise instead of accepting it. But it is, most likely, not that clear. The cost of such a ticket should discourage too much of that kind of discretion, without eliminating it. (Of course, if different people are allocated different degrees of discretion because income varies unfairly, that is another flaw in the whole system, not something to be worked out in this example.)

I think legal systems (especially those with common-law histories) are paraconsistent by design, and handle the conflict with punishments in a range of degrees. We all live late enough in the history of our legal processes that we encounter fewer outright exceptions, and we forget the history, but absolute internal consistency was not an initial goal in many legal systems. Judging involved judgement calls on purpose.

The Common Law tradition in England and some of its colonies (including parts of the US) builds in long-term acceptance of the risk of breaking the law as a way of modifying the law itself.

Some examples in the Common Law countries that still apply where they are not officially overruled:

  • Marriage by affiliation: An unmarried woman is legally required to
    maintain some room of her own, shared only with blood relatives, other women, or children. But if she voluntarily shares a bedroom with a single man for long enough, reserving no other space of her own, she is then 'effectively married' to him, she can live there indefinitely, all property in that room is shared, and her children will be his responsibility. (I think this is no longer applicable anywhere. But many places never overruled it until they allowed gay marriage, at which point it becomes sexist. Parts of this concept were still the law in my home state until 2016.)
  • Easement of passage: If your land lies along an ordinary route with a history of common use, you cannot prevent people from trespassing. So trespassing often enough makes it not trespassing.
  • Squatting: If you illegally occupy a space set aside for a different purpose for long enough without encountering charges from anyone asserting their right to use it for that purpose, it no longer has that purpose, and you have the right to stay there.

I think this kind of planned self-correction of neglected rights or responsibilities makes perfect sense, and these are reasonable laws. But they make no sense unless you accept the argument that supports 'taking the ticket' above.

  • Can you please edit your answer to explain the third paragraph a bit more? Usually, there are costs associated with challenging a traffic ticket, such as having to take time off of work. A person could decide that they are morally right, that the law should be changed so driving someone to the ER is a defense against speeding, and that they will not challenge the ticket in court because the costs of doing so out way the benefits even if they win.
    – E Tam
    May 28, 2021 at 19:19
  • @ETam. They could, but the system does not have to agree with them. They are making a decision that could kill someone else, instead of the person sitting in the seat next to them. So this is a 'trolley problem' instance. We might want to encourage a conservative approach to that, including the odds the ambulance would be faster. So they are making a decision with which others do not need to agree, whether or not they are right. No legal system can handle all such options. If handling them is neccessary, your premise of a perfect legal system is impossible. May 28, 2021 at 21:25

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