An English court holds that Stable Diffusion's weights are not an infringing copy of the images used to train it

2025-11-04UK

Getty Images (US) Inc v Stability AI Ltd [2025] EWHC 2863 (Ch) (4 November 2025) (Joanna Smith J), Case No. IL-2023-000007

Getty Images sued Stability AI in the High Court over the Stable Diffusion image models. By the end of trial Getty had abandoned its primary copyright claim over training, there being no evidence of training in the United Kingdom, its claim over outputs, because prompt blocking had achieved the relief sought, and its database right claim. What remained was secondary infringement under sections 22 and 23 of the Copyright, Designs and Patents Act 1988, on the theory that the model is an "infringing copy" because making its weights would have infringed if done in the United Kingdom, trade mark claims under section 10 of the Trade Marks Act 1994 over Getty and iStock watermarks in outputs, and passing off. The judgment records that the model does not store training data. Mrs Justice Joanna Smith held that an "article" can be intangible, but that an infringing copy must at some time have contained or stored a copy of the work, and because Getty accepted, as both sides' experts agreed, that the weights contain no copies of its works, the secondary infringement claim failed. The trade mark claims succeeded only for a few watermarked outputs of the first two model versions, findings described as extremely limited; the claims for the SD XL and v1.6 models and under section 10(3) failed, and passing off added nothing.

What it changesThe judgment accepts, on agreed expert evidence, that trained weights do not contain the works they were trained on, and it treats the model as the developer's own technical object rather than a copy of anyone's images. That supports protecting weights as a trade secret and claiming the training method and model structure as inventions in their own right. The case was decided on expert evidence of what the parameters represent, and a patent specification should carry the same kind of explanation, because what the weights encode is also what written description and sufficiency will be measured against. The territorial point cuts across patents too: Getty abandoned the training claim for want of evidence of training in the United Kingdom, and a training-method claim is likewise infringed only where training is done, so portfolios need claims to the trained model, the inference system and its uses in the markets where the model is deployed. This is a first-instance judgment on a narrowed case.