Even you example is more precise that most laws.

For example Indiana recently changed their Turn signal law from "Must put in on 300 feet before a lane change" to "Must signal in a reasonable time"

WTF is a reasonable time... well what ever time the cop, judge, or prosecutors says it is

Right.

The programmer in me fumes at that imprecision.

The human in me says "thank God". Because there a myriad valid times you cannot turn on signal 300ft before lane change, but you should always do it in reasonable time :)

If I turn on a new street and there's a car parked 200ft down the lane or if a kid jumps on the road or if I become aware of an obstacle or a car cuts me off or I want to give somebody room at a merge etc etc... I may not be able to do it in 300ft but I should still try to do it in reasonable time.

There's no "winning". Overly precise is inhumane in some scenarios, Overly vague is inhumane in others.

Perhaps we could both give a vague description, and also a precise condition which is to be considered a sufficient but not necessary condition for the vague condition to be true?

Such as “must signal within a reasonable time (signaling at least 300ft beforehand while not speeding is to be considered a sufficient condition for signaling within a reasonable time)”

Downside: that could make laws even longer.

Hm, what if laws had, like, in a separate document, a list of a number of examples of scenarios along with how the law is to be interpreted in those scenarios? Though I guess that’s maybe kind of the sort of thing that precedent is for?

That sounds like case law? Eg: It’s why we call “Roe v Wade” as we do.

What’s the difference between “precedent” and “case law”? I had thought that when I said “Though I guess that’s maybe kind of the sort of thing that precedent is for?” that that covered things like citing “Roe v. Wade”.

I’m not a lawyer, I just play one on HN.

I thought precedent was a broader term that also covers accepted practices or processes.

> The human in me says "thank God".

You're more charitable than me: I assume there will be infinitely more times where the imprecision is used for probable cause for a stop, than there will be times where someone was going to pull you over because you properly responded to a road hazard

Oh fair enough.

But I think there's a difference between "intent of change" and "abuse of change" / "threat surface of the change". Sometimes there's a clear, direct line between the two, but (and this is me being charitable:) I think a lot of the time there isn't. Which is to say, I don't think it's necessarily a contradiction that a) The law was changed to make things better/easier for people while b) In actual real world it can or will be abused a lot to make arbitrary trouble - the latter will depend a lot on place/politics/corruption/culture/societal norms/power balance/etc.

Reasonable time is determined by case law, and when it's a judge deciding, it's the judge's estimation of what a reasonable juror in that jurisdiction would think about the case. It's not as woozy as it seems, and is usually called an objective standard in the legal jargon. It's something that could conceivably be determined by a computer looking at all the factors that a judge would look at, and/or the relevant jury instructions that might frame the issue for a jury.

It doesn't have to be precise. The founder should wear his own glasses, go to court to defend himself and use a fusion technique: have a lawyer and his AI both reach through his glasses. If he loses, he says, "we have a bit of work to do", if he wins, he wins. Either way, great publicity.

Many legal things are evaluated lazily: the law may not specify exactly what the vehicle is, but if such need arises, there are tools, like precedents and analogy, to answer this question.

The way to think about it is like a logical evaluation shortcut:

  if not ADA_EXEMPT and IS_VEHICLE:
    DISALLOW_IN_PARK

Since wheelchairs are ADA exempt, a question of whether it's a vehicle will probably never be risen.

Using the IT analogy, it's less like C++, where each statement must pass compiler checks for the application to merely start, but more like a Python, where some illegal stuff may peacefully exist as long as it's never invoked.

EDIT: grammar

None of ADA_EXEMPT, IS_VEHICLE, or DISALLOW_IN_PARK can be easily formally defined. And the mere mention of "wheelchair" adds an additional ADA-related logic exemption. What about bicycles? Strollers? Unicycles? Shopping carts? Skateboards?

And even if IS_VEHICLE was formally defined, that doesn't help, because the concept isn't reusable. It's perfectly normal for "No vehicles allowed in park" and "No vehicles allowed in playground" to have different definitions of what counts as a vehicle, based on what would seem reasonable to a jury

It's silly for people here to insist that the law be a formal system. It's impossible. Common Law uses judicial precedent to fill in ambiguities as they turn into actual disputes. If you had to formally define everything, then a) it would run into the various Incompleteness Theorems in logic (like Goedel's) and the Principle of Explosion, so it would go hilariously wrong b) No law would ever get passed, as people would spend years trying and failing to recursively define every term.

Appropriately enough, Gödel had this very problem when getting US citizenship, where he tried to argue that the law had a logical problem:

"On December 5, 1947, Einstein and Morgenstern accompanied Gödel to his U.S. citizenship exam, where they acted as witnesses. Gödel had confided in them that he had discovered an inconsistency in the U.S. Constitution that could allow the U.S. to become a dictatorship; this has since been dubbed Gödel's Loophole. Einstein and Morgenstern were concerned that their friend's unpredictable behavior might jeopardize his application. The judge turned out to be Phillip Forman, who knew Einstein and had administered the oath at Einstein's own citizenship hearing. Everything went smoothly until Forman happened to ask Gödel if he thought a dictatorship like the Nazi regime could happen in the U.S. Gödel then started to explain his discovery to Forman. Forman understood what was going on, cut Gödel off, and moved the hearing on to other questions and a routine conclusion"

https://en.wikipedia.org/wiki/Kurt_G%C3%B6del#Princeton,_Ein...

>Many legal things are evaluated lazily: the law may not specify exactly what the vehicle is, but if such need arises, there are tools, like precedents and analogy, to answer this question.

That's how common law and precedents work in the US system. Case A from 1924 said cars were vehicles, but bikes weren't. Case B from 1965 said e-bikes weren't vehicles. Case C said motorcycles were vehicles. And then the judge analogizes the facts and find that an electric motorcycle is a vehicle so long as its not a e-bike.

But the administrative law side of things works the opposite. They publish a regulation just saying "e-bikes above a certain weight qualify as vehicles under Law X."

An example in the UK yesterday. Climate protesters glued themselves to a petrol tanker and were charged with tampering with a motor vehicle. The protesters argued that the bit with the petrol was a trailer, not a motor vehicle. The judge agreed and acquitted them. https://www.bbc.com/news/uk-england-london-64403074

My point was not about necessary ambiguity where precision is not attainable. It was about todays inability of the legal professions to write concise conditions within contracts or laws.

E.g. as someone else said in this threat, there is useful ambiguity in requirements like: „within reasonable time“. But if you are enumerating a bunch of things and their relationships, ambiguity is often not what you want, but what you get without some clear syntax.

In my experience it’s not uncommon to stumble upon legal texts like „a, b and c or d then …“. But what does that mean? Is this supposed to be „(a && b && c) || d“ or „(a && b) && (c || d)“? That’s stuff that could easily be clarified at times of writing by just using parenthesis. Or maybe using actual lists with one item per line instead of stupid csv embedded in your sentences.