Simon Willison examines a legal and ethical controversy sparked by the chardet 7.0.0 release, where maintainer Dan Blanchard used Claude Code to produce a ground-up MIT-licensed rewrite of the LGPL-licensed Python library. Original author Mark Pilgrim contested the relicensing, arguing it violates the LGPL since Blanchard had extensive exposure to the original codebase. Blanchard counters that the resulting code is structurally independent, backed by plagiarism detection showing under 2% similarity. The case raises unresolved questions: whether an AI-assisted rewrite by someone deeply familiar with the original qualifies as a clean-room implementation, whether Claude's training on the original codebase matters legally, and whether using the same PyPI package name undermines the argument. Willison sees this as a preview of broader commercial IP disputes as coding agents make clean-room-style reimplementations fast and cheap.
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