California AI Transparency Act Now Operative — Law Firms Building Client-Facing AI Tools Face Immediate Compliance Review

California's AI Transparency Act (SB 942, as amended by AB 853) became operative on August 2, 2026 — the same day as EU AI Act Article 50 — requiring covered generative AI providers (platforms with more than 1 million monthly users) to include machine-detectable disclosures in AI-generated content. For law firms using California-based or California-operative generative AI platforms to produce client-facing content — draft agreements, memos, legal analyses distributed electronically — the Act creates a disclosure question that will recur in client conversations. Law firms are not themselves covered providers under the Act's current definition, but the platforms they use are; the machine-readable disclosure marks embedded in AI-generated documents are detectable by clients using disclosure-checking tools. For general counsel receiving AI-assisted legal work product from outside counsel, the California Act provides a technical mechanism to identify undisclosed AI-generated content — a pressure point that will surface in client conversations in California-heavy practice areas including technology, entertainment, and VC.