Cornell International Law Journal


Peacetime espionage, Customary international law, Intelligence gathering


This Article demonstrates that peacetime espionage does not benefit from permissive customary international law exceptions. The mainstream view contends that, though peacetime espionage may contravene international law, developments in customary international law (CIL) nevertheless undercut State responsibility for such conduct. The gist of this view is that acts of espionage benefit from permissive CIL exceptions because its practice is widespread and accepted within the international society. However, the mainstream literature has rarely-if ever-meaningfully engaged with the practice of espionage in an effort to tease out the objective and subjective elements supportive of customary espionage exceptions. This Article closes this gap and debunks the mainstream view. We show that, although widespread, most acts of espionage are committed in secret and, as such, they cannot qualify as State practice for the purpose of CIL formation. We further demonstrate that States have failed to issue expressions of the subjective element in support of customary espionage exceptions. We conclude by suggesting that, while States are entitled to develop customary espionage exceptions in the future, for now they have yet to come out of the legal wilderness.