From Biosignatures to First Contact: Planetary Protection, Scientific Verification and International Legal Governance

This article examines how existing scientific and legal institutions could govern a scientifically credible discovery of extraterrestrial life or intelligence. The paper deliberately excludes unidentified anomalous phenomena, unverified visitation claims, and speculative narratives unsupported by reproducible evidence. Its starting point is that astrobiology and international space governance already contain important fragments of a post-detection architecture: life-detection frameworks, planetary-protection rules, the Outer Space Treaty, COSPAR policy, the International Academy of Astronautics’ 2026 SETI principles, frequency-protection pathways referenced by the IAA principles, and United Nations mechanisms for international coordination. The article makes three contributions. First, it develops a legal-scientific taxonomy that distinguishes remote biosignatures, in situ biological evidence, returned extraterrestrial material, and verified technosignatures because each generates different legal and governance questions. Second, it maps the existing fragmented institutional architecture and identifies the gap between scientific verification and collective decision authority. Third, it proposes a staged Post-Detection Governance Framework covering independent verification, evidence classification, planetary-protection review, international notification, data preservation, risk assessment, coordinated public communication, and any decision concerning reply. The article argues that a credible framework should emerge from existing institutions rather than from fictional assumptions about extraterrestrial actors. The deeper legal problem is not whether international law already recognizes extraterrestrial legal personality; it is whether humanity has procedures for governing its own conduct when evidence of life beyond Earth becomes scientifically credible.