Greater public awareness of the occurrence of sexual assault has led to the creation of mobile phone apps designed to facilitate consent between sexual partners. These apps exhibit serious practical shortcomings in realistic contexts; however, in this paper I consider the hypothetical case in which these practical shortcomings are absent. The prospect of this viable consent app creates an interesting challenge for consequentialism – one that is comparable to the objection that the theory justifies killing innocent persons to prevent large (...) numbers of less serious harms like experiencing brief, painful headaches. I outline and reject the most straightforward way for consequentialists to address this challenge, and I argue that the empirical calculations at stake reveal something rarely appreciated: consequentialists ought to sometimes favour reinforcing deontological constraints in common-sense morality rather than seeking to undermine them. (shrink)