Current guardrails are a mix of industry best practices, voluntary screening and government regulation. Many synthesis companies willingly participate in sequence screening initiatives that flag orders matching known pathogens or dangerous sequences. Some generative AI companies also apply content and model-safety policies that block prompts about biological-harm instructions. But in the open letter, experts across the fields of science, technology, public policy, academia and law are proposing tougher measures. The public letter shows a consensus that the risks of AI-developed bioweapons des