She introduced the breathalyser to combat the then recently acknowledged crisis of drink-driving. Castle said she was "ready to risk unpopularity" by introducing the measures if it meant saving lives. She was challenged by a BBC journalist on "The World This Weekend", who described the policy as a "rotten idea" and asked her: "You're only a woman, you don't drive, what do you know about it?" In the 12 months following the introduction of the breathalyser, Government figures revealed road deaths had dropped by 16.5%.