The argument that a rewrite is a copyright violation because they are familiar with the code base is not fully sound.

"Insider Knowledge" is not relevant for copyright law. That is more in the space of patent law then copyright law.

Or else a artist having seen a picture of a sunset over an empty ocean wouldn't be allowed to pain another sunset over an empty ocean as people could claim copyright violation.

Through what is a violation is, if you place the code side by side and try to circumvent copyright law by just rephrasing the exact same code.

This also means that if you give an AI access to a code base and tell it to produce a new code base doing the same (or similar) it will most likely be ruled as copyright violation as it's pretty much a side by side rewriting.

But you very much can rewrite a project under new license even if you have in depth knowledge. IFF you don't have the old project open/look at it while doing so. Rewrite it from scratch. And don't just rewrite the same code from memory, but instead write fully new code producing the same/similar outputs.

Through while doing so is not per-se illegal, it is legally very attackable. As you will have a hard time defending such a rewrite from copyright claims (except if it's internally so completely different that it stops any claims of "being a copy", e.g. you use complete different algorithms, architecture, etc. to produce the same results in a different way).

In the end while technically "legally hard to defend" != "illegal", for companies it's most times best to treat it the same.

> "Insider Knowledge" is not relevant for copyright law. That is more in the space of patent law then copyright law.

On the contrary. Except for discussions about punitive damages and so on, insider knowledge or lack thereof is completely irrelevant to patent law. If company A has a patent on something, they can assert said patent against company B regardless of whether any person in company B had ever seen or heard of company A and their patent. Company B could have a legal trail proving they invented their product that matches the patent from scratch with no outside knowledge, and that they had been doing this before company A had even filed their patent, and it wouldn't matter at all - company A, by virtue of filing and being granted a patent, has a legal monopoly on that invention.

In contrast, for copyright the right is intrinsically tied to the origin of a work. If you create a digital image that is entirely identical at the pixel level with a copyrighted work, and you can prove that you had never seen that original copyrighted work and you created your image completely independently, then you have not broken anyone's copyright and are free to sell copies of your own work. Even more, you have your own copyright over your own work, and can assert it over anyone that tries to copy your work without permission, despite an identical work existing and being owned by someone else.

Now, purely in principle this would remain true even if you had seen the other work. But in reality, it's impossible to convince any jury that you happened to produce, entirely out of your own creativity, an original work that is identical to a work you had seen before.

> But you very much can rewrite a project under new license even if you have in depth knowledge. IFF you don't have the old project open/look at it while doing so.

No, this is very much false. You will never be able to win a court case on this, as any significant similarity between your work and the original will be considered a copyright violation, per the preponderance of the evidence.

If I read Mario Puzo’s The Godfather and then proceed to write a structurally identical novel with many of the same story beats and character types, it will not be difficult to convince a jury exposed to these facts that I’ve created a derivative work.

On the other hand, if I can prove to the jury’s satisfaction that I’ve never been exposed to Puzo’s work in any form, it’s independent creation.

If the new maintainers used Claude as their “fancy code generator” (there’s a Claude.md file in the repository so it seems so) then it was almost certainly trained with the chardet source code.

> And don't just rewrite the same code from memory, but instead write fully new code producing the same/similar outputs.

How different does the new code have to be from the old code and how is that measured?

This is a bad argument.

Think of a rewrite (by a human or an LLM) as a translation. If you wrote a book in English and somebody translated it into Spanish, it'd still be a copyright issue. Same thing with translations.

That's very different to taking the idea of a body of work. So you can't copyright the idea of a pirate taking a princess hostage and a hero rescuing her. That's too generic. But even here there are limits. There have been lawsuits over artistic works being too similar.

Back to software, you can't copyright the idea of photo-editing software but you can copyright the source code that produces that software. If you can somehow prompt an LLM to produce photo editing software or if a person writes it themselves then you have what's generally referred to as a "cleanroom" implmentation and that's copyright-free (although you may have patent issues, which is a whole separate issue).

But even if you prompted an LLM that way, how did the LLM learn what it needed? Was the source code of another project an input in its training? This is a legal grey area, currently. But I suspect it's going to be a problem.

Hate to be "that guy" but in a corrupt legal system, which ours is, none of this matters. Who has the influence and dollars to make the decision theirs is all that matters.

I think you could have an LLM produce a written English detailed description of the complete logic of the program and tests.

Then use another LLM to produce code from that spec.

This would be similar to the cleanroom technique.