Text AI watermarks will always be trivial to remove

The European Union AI Act will begin to be enforceable in August 2026, one month from now1. One of the biggest new requirements is Article 50, which requires all AI outputs to be “detectable as artificially generated”. In other words, if LLM providers want to do business in the EU, they will have to apply a watermark to their outputs2: some hidden signature that can be used to identify AI content. LLM text watermarking is a fascinating problem. Like the best engineering problems, it is theoretically hard to solve perfectly, but has multiple partial solutions: for instance, Google’s SynthID, and (as I’ll argue) some quiet Unicode trickery from OpenAI and Anthropic. It will be interesting to see how the AI labs navigate these tradeoffs before the end of the year. Why text watermarking is hard I wrote about AI watermarking at the end of last year in AI detection tools cannot prove that text is AI-generated. It’s easy to watermark an image, because digital images contain lots of noise…