 Hearn was admitted to the Victorian Bar in 1860, although he only occasionally practised as a barrister.In 1873, Hearn was appointed as the first Dean of the newly created Faculty of Law, lecturing in subjects such as constitutional law.In 1874 and 1877 he again stood unsuccessfully for parliament, evading the ban on professors running for election on the basis that as a dean, he had lost his professorial title.