 More recently some republicans have sidelined the notion of impunity of interference in favour of that of ‘ignorability’ of interference (Ingham and Lovett 2019). I am free to make certain choices if the structure of effective societal norms, whether legal or customary, is such as to constrain the ability of anyone else to frustrate those choices, to the point where the possibility of such frustration, despite existing, is remote enough to be something I can ignore. Once I can ignore that possibility, then the structure of effective norms makes me safe by removing any sense of exposure to interference. Defenders of the negative concept of liberty might respond to this move by saying that the criterion of ignorability looks very much like a criterion of trivially low probability: we consider ourselves free to do x to the extent that the system of enforced norms deters others’ prevention of x in such a way as to make that prevention improbable.