Abstract
Stephen Gardiner and Augustin Fragnière suggest replacing the Oxford Principles for the governance of climate engineering (CE) with their 10 Tollgate Principles (Gardiner & Fragnière, 2018). Like the Oxford Principles, the Tollgate Principles offer abstract, high-level guidance. Translating either set of principles into actual policies or governance mechanisms therefore requires considerable effort. In this commentary, I offer some suggestions for putting the Tollgate Principles into practice, paying special attention to the notions of ‘ethically defensible forms’ of CE and ‘well-founded ethical norms’.