In the present paper the author considers a challenge to libertarianism posed by G.A. Cohen. The charge issued by Cohen says that libertarianism defines freedom in terms of justice and justice in terms of freedom. The paper deals with an aspect of this charge as expressed by one of Cohen’s thought experiments according to which it is not the case that the answer to the question whether person B forces person A to do φ depends on whether person B’s actions are legitimate or not. Employing the Hohfeldian analysis of fundamental jural conceptions, the author demonstrates that if person B’s actions are legitimate, then making person A to do φ cannot, at pains of contradiction, be considered forcing. If person B is at a liberty to make person A to do φ, then person B cannot at the same time and in the same respect be at duty not to make person A to do φ. Yet, this is exactly what would follow if we adopted the stance that person B’s legitimate actions force person A to do φ. If they forced person A, then the expenditure of whatever labour needed to do φ would not be a voluntary expenditure and thereby would constitute a violation of person A’s rights to this labour. However, if person A’s rights were violated by person B’s actions, then via Hohfeldian Correlativity Axiom person B would have to be at duty not to undertake these actions. Yet, the whole reasoning started from the assumption that person B is at liberty to undertake them.