Ruggles was educated as a barrister at the Temple, an Inn of Court, and eventually became a bencher of Lincoln's Inn and the honourable society of the Inner Temple. He completed two works in the 1790s that are considered to be of great importance to legal, social and economic historians. The first was entitled 'The Barrister, or, Strictures on the Education Proper for the Bar' (1792). Within this, his major educational recommendation was that admission to the Inns of Court be conditioned on the completion of a bachelor's degree in arts or law at Cambridge or Oxford. Only such a background - particularly in ancient and modern languages, philosophy, history, and poetry - would allow barristers and practitioners to rise above their own self-interest and develop integrity of mind at the bar.
His second work, 'The history of the poor, their rights, duties, and the laws respecting them. In a series of letters' (1793-4), contributed importantly to the debate on poverty in late-eighteenth century England. Ruggles, deeply intent on improving the deplorable condition of the poor, eventually concluded that poverty stemmed from the indolence, improvidence, and moral laxity of the labouring class, especially "the baneful and seducing habit of drinking strong liquors".
It was through his first wife that his connection to Elmbridge comes. Jane Anne, whom he married in 1779, was the daughter of a John Freeland of Cobham and it is highly likely that he spent some time there in the twenty-three years between their marriage and Jane Anne's death.