He obtained the Dr.jur. (doctor of laws) degree in 1907 from the University of Heidelberg with a dissertation that was published the following year as Das Recht über sich selbst (The right over oneself). The University of Heidelberg, however, recognized only that portion of the dissertation entitled Die kriminalistische Bedeutung des Selbstmordes (The criminal significance of suicide). In the complete dissertation, Hiller defended not only the right to suicide, but also the right to abortion and to engage in same-sex sexual relations. .