The subjected status of the coloni equalled them to persons alieni iuris, as slaves were too, but they were still free. It made marriages with those not in this way subjected with regard to the transmission of status ‘unequal’. It implies that children follow the status of the mother. This ‘unequal marriage’ and its consequence was introduced by earlier laws. To prevent the children out of marriages of a colonus with a not subjected woman being not subjected, the senatusconsultum Claudianum was applied. That made children follow the status of the father. The abolition of the senatusconsultum led Justinian to introduce the faculty of estate owners to recall coloni from such marriages in order to prevent the loss of labour force. CJ 11.48.19 established that every colonus after thirty years of service was no longer alieni iuris and thus subjected to their estate owner, but free from his control over him and his property. Such coloni are called ‘free’ coloni (coloni liberi). They remained tied to the estate and had to render services and to pay poll tax, but could now fulfill public functions as no longer being of subjected status.

This chapter presents Grotius’ ars politica that deals with what is useful in practice, different from the ars iuris that deals with issues of justice.Philosophically eclectic, descriptive and non-perfectionist, Grotius’ ars politica is directed at understanding and guiding the organisation of power (potestas) and interest (utile) in human live, on two levels: a. the metalevel of theoretical discussion comparing and integrating different approaches to the topic, and b. the practical level of providing answers to political challenges. As agency is central, so is autonomy, and sovereignty.