Ben Saul takes us back to legal antecedents of modern terrorism laws, unfolding a story of how increases in the level and sophistication of law enforcement cooperation against anarchists led eventually to the attempted negotiation under League auspices of an anti-terrorism convention, the AIDP’s attempts to draft a code of common offences for mankind including terrorism, and the work of the International Bureau for the Unification of Criminal Laws (IBUCL) in trying to unify national criminal laws under the League.