Britain is now rabies free  Nevertheless, Britain' s strict quarantine of imported domesticated animals, designed to prevent widespread outbreaks of rabies there, cannot succeed indefinitely in preventing such outbreaks  Bats, which are very susceptible to rabies, fly into Britain from continental Europe
Since wild bats cannot be quarantined, this policy cannot control rabies spread by wild bats
arguing that a certain policy is bound to fail because an event that is likely to defeat the aim of the policy falls outside the policy's influence