What is effective legislation? Is it a matter of intuition, luck or the result of evidence based law making? Can it be consciously ‘engineered’? This book advances the novel idea that legislative effectiveness is the result of complex ‘mechanics’ in the conceptualisation, design and drafting of four elements inherent in every law: purpose, content, context and results. It concludes that effectiveness can be achieved with conceptual and methodological insights that guide the specific choices of lawmakers when designing and drafting legislation.