We review the major findings concerning omission bias and protected values (PVs). PVs are values that are absolute, hence protected from trade-offs with other values. We argue that PVs against omissions are relatively rare, since a prohibited omission would be an injunction to act, which could create infinite obligations, and we provide support for this argument. We also replicate and extend earlier findings of a correlation between PVs and omission bias, the bias to favor harms of omission over equal or greater harms from action. We discuss the nature of omission bias and its relation to other biases. We also find that, although emotional responses are correlated with biases, we can manipulate apparent emotional responses without affecting PVs or omission bias. We thus argue that emotions are not the only cause of biases.