Now imagine how buggy legal documents are when they're rewritten fresh each time, rather than using open source libraries and subroutines.

Luckily things are interpreted by human judges who can use discretion and interpret things in a sort of "do what I mean" way, so "bugginess" isn't as big of an issue as it is in coding.

This is as true as ever changing compiler extensions like undefined behaviour optimizations have proven a success for maintainable and portablility.

this is the crux of the thing.

Well, until we reach smarter-than-human AI, you ultimately have to base everything in society on trust. That's why I actually find the ideas around trustless systems to be potentially dangerous.

Discretion of a human judge is grease on the gears of law.

Legal documents are hardly "rewritten fresh each time". Lawyers have standard legal templates for things like contracts for example, where only few things change.

Moreover the content and legal rules predetermines what will be written in such legal documents down to the phrasing. While there will be differences, it's not "free writing"/"express yourself" kind of thing.

In software, it's considered poor coding practice for code to be repeated more than once. If lawyers use templates so often and only a few things change, why don't they employ something similar? E.g. here's standardLeaseContract(); difference1(); difference2(); difference3();

To me it seems this would make things much clearer to parties involved, and reduce opportunities for abuse compared to many pages of boilerplate and only a few lines that matter.

Because as in software, so in law, you must deliver an end product that has the instructions expanded with the differences included in. You don't give templates, you dive the rendered result. A tech savvy law firm could of course use templates to define what that would be.

That said, a lot of state law is kind of like what you describe. An initial law, and tons of differences applied on it. E.g. article 3242 clarifies article 432 and adds the provision to do so and so.

I don't think that's quite right. There is often a "standard" way write certain things. Then there's a bug exposed - that wording lost in a court case. Now people stop using that wording. They try different alternate wordings. Eventually, there's kind of a convergence on a new "standard" way to write it.

Two disclaimers. First, IANAL. Second, "standard" really means "a lot of people do it this way", not "this is recognized as the right way to do it".

Except this doesn't happen. If a lawyer plots a 1k+ page contract down on your table to sign, he probably didn't write it from scratch for you. If the lawyer has been at this for a while, he or she has a list of likely vary similar contracts that they drew most of the language from and then modified for the needs of you and the other entities (we don't like the clause, we want to be protected against this, etc.).