According to Aquinas, the issue of determination (derivatio per modum determinationis) is bounded to other general principles present in his own philosophical thought and theory of justice. Among these, the problem of positive law's coactive force, the world's government by means of second causes, the immutability of natural law, and the limitations of human law -which is only to punish the foulest vices-, are of particular importance. In this work, I would like to address these four problems -which are actually presuppositions of the way of determination-, explaining how Francisco Suarez received these ideas from the medieval thinker.