Born in London, he was educated at Eton College and Peterhouse, Cambridge.[2] He trained as a lawyer at Lincoln's Inn, where he was called to the bar (qualified as a barrister) in 1775. In addition to his legal practice, he became a prolific writer on the law and political topics. In politics, he was an advocate of parliamentary and other reforms, identifying with the Foxite Whig faction. He also engaged in voluminous correspondence with prominent authors.
His legal career was ended by a case in Stanton, Suffolk. On the night of 3 October 1799, Sarah Lloyd, a 22 year old servant, was incited by a suitor to steal 40 shillings. She was caught, tried, and sentenced to death by hanging. Capel Lofft fought[why?] strenuously but unsuccessfully for a reprieve. Lloyd was to be executed on 23 April 1800 in Bury St Edmunds. Lofft accompanied the cart transporting Lloyd on that morning, holding an umbrella over Lloyd to shield her from rain, and remained by her side until she was hanged. The authorities[which?] took a dim view of Lofft's fight on Lloyd's behalf,[why?] and he was struck off the Roll (list of qualified lawyers).[3]
Lofft wrote the preface to poet and former Quaker Thomas 'Clio' Rickman's An Ode, in Celebration of the Emancipation Of The Blacks of Saint Domingo, November 29, 1803.[4][5] He commended Toussaint Louverture – "of whom Posterity will know how to speak" – and hoped that "a Nation [Haiti] which has emerged into Freedom should prove itself capable and worthy of the blessings [sic] by its use of it".[4] He became the patron of Robert Bloomfield, the author of The Farmer's Boy, and was responsible for the publication of that work. Byron, in a note to his English Bards and Scotch Reviewers, ridiculed Lofft as "the Maecenas of shoemakers and preface-writer general to distressed versemen; a kind of gratis accoucheur to those who wish to be delivered of rhyme, but do not know how to bring forth."
In 1816 Lofft moved to Europe for his daughters' education.[12] He died in 1824 aged 72 at Montcalieri, near Turin.[13] His 'law and miscellaneous' library was auctioned in London by R. H. Evans (along with the books of Henry Cooper Esq) on 8 June 1825. A copy of the catalogue is at Cambridge University Library (shelfmark Munby.c.129(9)).