The use of optogenetics to inhibit the activity of defined populations of neurons with high temporal precision is of enormous value for researchers attempting to dissect inaccessible neural circuits in the brain. Chuong et al. now report the development of a red-light-sensitive chloride pump, named Jaws, which is capable of driving neural hyperpolarization. The authors showed that, owing to the ability of red light to penetrate tissue, Jaws can enable non-invasive transcranial inhibition of activity in the mouse brain. In addition, activation of Jaws was used to restore photosensory activity in the retinae of mice modelling the degenerative condition retinitis pigmentosa, suggesting that this opsin may also have clinical utility.