Prompts, privilege & discovery
Concord Music Group, Inc. v. Anthropic PBC
A three-order sequence protected attorney testing, allowed aggregate facts, and compelled post-suit prompts used by planned witnesses.
Mixed production01
Case background
Material facts
Anthropic sought music publishers’ testing prompts while the publishers sought a large sample of third-party Claude prompt-output pairs. Later disputes focused on investigators and client witnesses who would testify about post-suit testing.
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The decision
The court’s ruling
Failed pre-suit attorney testing remained opinion work product, while Anthropic had to produce a confidential random sample of five million prompt-output pairs. Aggregate testing facts were discoverable, and post-suit prompts used by planned witnesses were later compelled because the investigation had been put at issue.
Why it matters
What the decision means
The orders draw a direct boundary. Private attorney testing remains protected, but a party that offers witnesses or favorable outputs must disclose the prompts and process needed to test that evidence.
Limit of the ruling. These are magistrate-level, fact-specific orders. The third-party conversation sample remained protected discovery, not public disclosure.
Primary reading