Mastodawn

The chardet open source library relicensed from LGPL to MIT two days ago thanks to a Claude Code assisted "clean room" rewrite - but original author Mark Pilgrim is disputing that the way this was done justifies the change in license - my notes here: https://simonwillison.net/2026/Mar/5/chardet/

Can coding agents relicense open source through a “clean room” implementation of code?

Over the past few months it’s become clear that coding agents are extraordinarily good at building a weird version of a “clean room” implementation of code. The most famous version …

Simon Willison’s Weblog

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Gordon Messmer Mar 5

@simon

"There are several twists that make this case particularly hard to confidently resolve:"

I really expected one of them to be that LLM output isn't subject to copyright under US law. Since a license is a grant of permissions that would not otherwise exist due to copyright, applying a license to LLM output doesn't make any sense.

No one needs explicit permission to use LLM output.

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Zegnat

@gordonmessmer @simon I came to comment the same thing. I would go as far as saying that if the argument for the clean room is that all code was written by Claude Code and not a human, that *must* then lead to the conclusion that the entire code base is not licensed MIT but rather a rare occurance of what Creative Commons calls “No Known Copyright” (https://creativecommons.org/public-domain/pdm/).

Public Domain Mark - Creative Commons

“No Known Copyright” Our Public Domain Mark enables works that are no longer restricted by copyright to be marked as such in a standard and simple way, making them easily discoverable and available to others. Many cultural heritage institutions including museums, libraries and other curators are knowledgeable about the copyright status of paintings, books and…

Creative Commons