🛡️Claude's New System Prompt Bans Song Lyrics Outright
TL;DR
Anthropic's updated Claude system prompt adds a hard block on reproducing song lyrics, poems and book passages, in whole or in part. Simon Willison diffed Fable 5 against 5.1 and found new copyright rules, a pre-1929 carve-out, and a stated June 2026 knowledge cutoff.
Anthropic's updated Claude system prompt adds a hard block on reproducing song lyrics, poems and book passages, in whole or in part. Simon Willison diffed Fable 5 against 5.1 and found new copyright rules, a pre-1929 carve-out, and a stated June 2026 knowledge cutoff.
Key Points
Posted Sept 2, 2026, diffing Anthropic's published consumer system prompts
New rule covers a single chorus, hook, or lines pasted in one at a time
Works first published before 1929 are allowed; Claude declines when unsure
Prompt also blocks drawing copyrighted characters and logos
Landed days after Sony Music Publishing and Warner Chappell sued Anthropic
Why It Matters
Anthropic publishes prompt history, so you can watch legal exposure turn into product behavior line by line. Almost no other lab hands you that trace, and it is the cheapest available lesson in AI copyright risk.
Quick Facts
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