According to Patrick Polden, his "career ridiculed the noble ideals of the bar".
In 1824 he graduated BA According to John Stuart Mill, Austin as undergraduate was an influential exponent of the ideas of Jeremy Bentham; and he had a reputation for brilliance as one of a group of contemporaries that included Thomas Babington Macaulay, Winthrop Mackworth Praed, John Moultrie, Edward Strutt, John Romilly, Charles Buller, and Alexander James Edmund Cockburn.
Having chosen law as a profession, Austin entered as a student at the Middle Temple, read in the chambers of Sir William Follett, then in the height of his fame as an advocate, and was called to the bar in 1827.
Austin was the undisputed leader of the parliamentary bar, the group of barristers who specialised in private bill procedure.
In 1847, at the height of the railway mania, his income was enormous — estimates vary from £40,000 to £100,000.
He married, in 1856, Harriet Jane, daughter of Captain Ralph Mitford Preston Ingelby.