1. Proportionality crossing borders : why is it still difficult to recognise sparrows and cannons / Sofia Ranchordas and Boudewijn de Waard 2. The principle of proportionality in German administrative law / Nikolaus Marsch and Vanessa Tunsmeyer 3. Proportionality in French administrative law / Yoan Sanchez 4. Proportionality in English law / A.C.L. Davies and J.R. Williams 5. Proportionality in Dutch administrative law / Boudewijn de Waard 6. The principle of proportionality in European law / Catherine Haguenau-Moizard, Yoan Sanchez 7. Agency discretion, judicial review and 'proportionality' in U.S. administrative law / Jud Mathews 8. Concluding remarks / Sofia Ranchordas and Boudewijn de Waard.