Drawing on Sartre's account of violence, I argue that not only is bad faith inevitable in practice, but a limited bad faith is necessary for authenticity. Although violating the freedom of others is bad faith, it is impossible to never violate anyone's freedom. Moreover, and more fundamentally, the ontological structure of the foritself entails that the for-itself can only be authentic in the mode of not being authentic. Seeking to altogether avoid bad faith is bad faith, for it is an attempt to constitute oneself as essentially authentic, yet the for-itself has no preexisting essence. By recognizing one's complete responsibility for choosing bad faith, however, one limits one's bad faith. This limited bad faith is in fact necessary to authenticity, which is a project lived out in concrete situations and not a categorical moral law that forbids bad faith.