He was born in Nikolsburg/Mikulov, Moravia, a son of Perlin Lipmann, chief rabbi of Brandenburg. Perlin Lipmann and his children converted to Catholicism some time between 1735 - 1741. Joseph, who was baptized in his early youth, received his elementary education at the gymnasium of his native town Nikolsburg, and then studied philosophy at the University of Vienna. In 1749, he joined the regiment "Deutschmeister" as a private, advancing to the rank of corporal. On his discharge in 1754, he took a course in law at the University of Vienna and established himself as a counselor at law in the Austrian capital. From 1761 to 1763, he officiated as secretary of the Austrian "Arcierengarde". In 1763, he was appointed professor of political science at the University of Vienna, twice acting as rector magnificus. In 1779, he received the title of "Wirklicher Hofrath", and was in 1810 elected president of the Academy of Sciences, a position which he held until his death in Vienna. From 1765 to 1767 and from 1769 to 1775 Sonnenfels was editor of "Der Mann ohne Vorurtheil", in which paper he defended the liberal tendencies in literature. He improved the Vienna stage especially through his criticalworkBriefe über die Wienerische Schaubühne, in which he attacked the harlequin of the Vienna theater, causing this figure to be eliminated from the personnel of the stage. He was chiefly instrumental in bringing about the abolition of torture in Austria. Sonnenfels' attitude toward Lessing placed the former in a very unfavorable light, as it was due to his intrigues and jealousy that Lessing was not called to Vienna. Sonnenfels was severely condemned for his action in this affair.
Works
Specimen Juris Germanici de Remediis Juris, Juri Romano Incognitis, Vienna, 1757.
Ankündigung einer Teutschen Gesellschaft in Wien, Vienna 1761.
Grundsätze der Polizei, Handlung und Finanzwissenschaft, Vienna 1765–67.
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Briefe über die Wienerische Schaubühne, Vienna 1768.
Von der Verwandlung der Domänen in Bauerngüter, Vienna 1773.
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Abhandlung über die Aufhebung der Wuchergesetze, Vienna, 1791.
Ueber die Stimmenmehrheit bei Criminalurtheilen, Vienna, 1801.
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His Gesammelte Werke appeared in 10 volumes, and contained most of his belletristic works, poems, and dramas.