AI can rewrite open source code-but can it rewrite the license, too?

"Their claim that it is a 'complete rewrite' is irrelevant, since they had ample exposure to the originally licensed code (i.e., this is not a 'clean room' implementation). Adding a fancy code generator into the mix does not somehow grant them any additional rights. I respectfully insist that they revert the project to its original license."

"No file in the 7.0.0 codebase structurally resembles any file from any prior release. This is not a case of 'rewrote most of it but carried some files forward.' Nothing was carried forward. Blanchard was able to accomplish this by first specifying an architecture in a design document and writing out requirements to Claude Code, then starting in an empty repository with no access to the old source tree."

A licensing dispute arose over whether an AI-rewritten version of chardet software must retain the original LGPL license. Pilgrim argues the rewrite is derivative because the developer had extensive exposure to the original code, violating clean room principles. Blanchard counters that AI-generated code is qualitatively different, citing JPlag similarity analysis showing only 1.29 percent structural similarity between versions 7.0.0 and 6.0.0, compared to 80 percent similarity between earlier versions. Blanchard claims he achieved an "AI clean room" by creating a design document, instructing Claude AI to avoid GPL/LGPL code, and starting with an empty repository without access to the original source tree.

Read at Ars Technica