Where there's a will there's a way: ChatGPT is used more for science in countries where it is prohibited

Regulating AI has emerged as a key societal challenge, but which methods of regulation are effective is unclear. Here, we measure the effectiveness of restricting AI services geographically using the case of ChatGPT and science. OpenAI prohibits access to ChatGPT from several countries including China and Russia. If the restrictions are effective, there should be minimal use of ChatGPT in prohibited countries. Drawing on the finding that early versions of ChatGPT overrepresented distinctive words like "delve," we developed a simple ensemble classifier by training it on abstracts before and after ChatGPT "polishing". Testing on held-out abstracts and those where authors self-declared to have used AI for writing shows that our classifier substantially outperforms off-the-shelf LLM detectors like GPTZero and ZeroGPT. Applying the classifier to preprints from Arxiv, BioRxiv, and MedRxiv reveals that ChatGPT was used in approximately 12.6% of preprints by August 2023 and use was 7.7% higher in countries without legal access. Crucially, these patterns appeared before the first major legal LLM became widely available in China, the largest restricted-country preprint producer. ChatGPT use was associated with higher views and downloads, but not citations or journal placement. Overall, restricting ChatGPT geographically has proven ineffective in science and possibly other domains, likely due to widespread workarounds.