The Spartans' treatment of their Elean, Mantinean and Phliasian allies in the first half of the fourth century bc has damaged their reputation for obedience to secular and religious laws. This chapter argues that the Spartans' reputation for rule-following can be rescued to a considerable extent if we think about Greek interstate relations in a less black and white manner. The Spartans were well known for their obedience to their laws, as Demaratus' famous statement 'nomos is their master' ably demonstrates. But the Spartans were not noted merely for their obedience to secular laws or customs. The chapter re-examines how the Spartans policed the loyalty of their allies in the late fifth and early fourth centuries bc when Sparta's relationships with her Peloponnesian allies particularly Corinth, Mantinea and Elis were decidedly changeable and problematic, in order to better understand Spartan behaviour regarding religious and secular law.