One of his brothers was Edward Pennefather, who was also a distinguished barrister and judge, and ended his career as Lord Chief Justice of Ireland.
Their sons who reached adulthood were: Their daughters were: Pennefather employed the architect William Tinsley, later famous for his work in the United States, to rebuild Darling Hill.
He and his brother "the two Pennefathers" were among the leading practitioners in the Court of Chancery (Ireland), although Richard was generally regarded as a less gifted barrister than Edward.
[3] There is credible evidence of a plot to murder several unpopular landlords in the Doneraile area, notably Michael Creagh, the former High Sheriff of County Cork.
Several local landlords expressed their fears to the authorities that an uprising was imminent, and in April, two informers, Patrick Daly and his cousin Owen, came forward with evidence that at a fair in Rathclare, near Buttevant, a few days earlier, a number of men had entered a sworn agreement to kill several local landlords, including Michael Creagh.
A Special Commission was set up to try them consisting of Pennefather and Mr. Justice Torrens, with John Doherty, the Solicitor General for Ireland, prosecuting.
[3] That a major miscarriage of justice was averted owes a good deal to the eloquence of Daniel O'Connell but also to the integrity of the judges, Torrens and Pennefather.
[7] An inquiry by the House of Commons in 1856 into the alleged incapacity of a number of Irish High Court judges pointed to Pennefather's age and physical disabilities, but the Bar responded with so eloquent a tribute to his ability that the matter was dropped.
[6] The Dictionary of National Biography describes him as a "sound, able, and upright judge, skilled in the digestion and elucidation of evidence, courteous in his bearing and in criminal cases lenient".
[9] His conduct of the Doneraile Trials, and in particular his ruling that the prosecution have an absolute duty to disclose all relevant evidence to the accused, was cited with approval by the Supreme Court of Ireland in 2007.