Nine out of ten modern constitutions contain explicit emergency provisions, describing who can call a state of emergency (and under which conditions) and the additional powers government enjoys under a state of emergency. As states of emergency typically allocate additional powers to the executive, they lend themselves easily to abuse and provide political incentives to declare emergencies. In this paper, we analyze under what conditions government behavior under a state of emergency deviates from constitutional provisions and a de jure/de facto gap thus emerges. Such a gap can be caused by the unlawful declaration of an emergency, the noncompliance with constitutional provisions in the course of an emergency, or the perpetuation of a state of emergency beyond the constitutionally defined length. Based on a novel dataset comprising 853 emergency declarations, 115 are identified as unlawful. We find that events caused by political turmoil are more likely to be followed by an unlawful emergency than natural disasters. Autocratic governments are more likely to renege against the constitution than democratic governments.