As author, journalist, jurist and counsellor of state, Sonnenfels was an important representative of the Enlightenment in Austria. His aim was to reform the theatre in keeping with Enlightenment ideas. In 1770, despite opposition from actors of the comedy stage, he was appointed principal theatre censor. In the ‘Hanswurst controversy’ (1747–1783) he opposed Hanswurst comedies. Sonnenfels successfully advised Maria Theresa on administrative and legal reforms, for example the abolition of torture in 1776. He was a Freemason, belonging to the Zur wahren Eintracht lodge.