The view that agents are not obliged to do more than their initial fair shares when their fellow duty bearers fail to comply has prominent defenders, including Liam Murphy and David Miller. While Murphy thinks that asking agents to take up other agents’ slack would be unfair, Miller claims that slack-taking cannot be required because primary responsibility does not migrate from noncompliers to compliers. This paper argues, by contrast, that there are a number of circumstances in which there is a (...) duty to take up the slack even though it is unfair and even though responsibility stays where it is. The central claim is that what agents owe to third parties is a separate issue from how they relate to fellow duty bearers. This proposal also runs counter to familiar defenses of slack-taking that weigh its unfairness against the moral importance of the interests at stake for third parties. (shrink)