This paper examines the legitimacy of retrospective parental rights-claims through the lens of so-called ‘thwarted father’ cases: men who are unaware of their progeny’s existence until the window for establishing legal parentage (and associated rights) has passed. In some famous cases of thwarted fathers, courts have found that an injustice has been done which must be rectified by awarding retrospective parental rights and custody to those men, even when their genetic child has already lived for some extended period with their (...) adoptive parents. In this paper, I critically examine Norvin Richards’ liberty-based defence of the parental rights of these fathers. He argues that the decision to overturn an adoption in a thwarted father case is justified if we agree that a man’s contribution of sperm was indeed the first act of a parenthood project that he should have had the liberty right to continue. Although Richards’ account might allow us to say that a thwarted father has been wronged, justice cannot demand that the situation be rectified through specific performance (as in cases when property is stolen and justice requires that it be returned). (shrink)