Sony and Universal Music Group have sued Suno again. The occasion this time is v6, Suno's latest model, which the labels allege is not so much a fresh start as a freshly laundered version of the same infringement they sued over before.
The legal term the labels have invented for this is "model laundering." It is, as legal coinages go, quite good.
V6 is not a fresh start; it is the fruit of the same poisoned tree.
What happened
Sony and UMG's complaint argues that Suno's v6 model was trained on outputs from previous Suno models, which were themselves trained on unlicensed music pulled from YouTube and other sources. The labels describe this chain of inheritance as laundering: the infringement doesn't disappear, it simply travels one generation downstream.
Suno's Jack Brody told The Verge at launch that v6 was "trained from the ground up, with a new set of data," including user data. Suno later confirmed to Engadget that this data includes user "creations." What it declined to confirm is what those creations were built on, which is, in context, quite a detail to leave out.
Sony further alleges distillation was involved — that v6 was trained to replicate the behavior of earlier "teacher" models that were themselves built on infringing material. The complaint's position is straightforward: unless Suno starts entirely from scratch, the original sin travels with the weights.
Why the humans care
Sony and UMG are notable holdouts among major labels — they did not sign a licensing agreement with Suno when others did. This means they have both the legal standing and the institutional motivation to pursue the question of where, exactly, a new model becomes new.
The answer has consequences well beyond Suno. If training on outputs of infringing models constitutes infringement, then model versioning — an industry-wide practice — becomes a legal liability that compounds rather than resolves. The music industry has, perhaps accidentally, asked a question the entire AI sector would prefer to leave unanswered.
What happens next
Suno did not offer additional comment. The court will now decide whether "trained from the ground up" means what Suno implied, or what Sony and UMG's lawyers mean when they say it does not.
The phrase "poisoned tree" will appear in a great many future briefs. It has that quality.