John Penros or Penrose was a Cornish lawyer and judge who held high office as Lord Chief Justice of Ireland, and subsequently served as a High Court judge in England and Wales. Despite his professional eminence, he was guilty of "an extraordinary career of crime" which stretched over nearly thirty years. When the charges against him were eventually proved, he was removed from the Bench. He belonged to a landowning family based at Escalls near Land's End in Cornwall. He was a qualified advocate, but also became notorious as a law-breaker. Along with his associates John Trevarthian senior , and his son John Trevarthian junior he was for many years one of the principal disturbers of the peace in Cornwall. What was later described as his "remarkable career of crime" began about 1370. In 1383 he was indicted in Surrey for his role in the murder of Richard Eyre, a fellow Cornishman whose family had a long-standing feud with the Trevarthians. The following year an arrest warrant on the charge of murder was issued for his apprehension, but was later withdrawn, apparently on the ground that he was not the principal in the murder. The list of serious crimes of which the Trevarthians were accused, and to which Penrose was an accessory, grew to a remarkable length: it included their private war with the Eyre family, which had resulted in the murder of Richard Eyre in 1383, as well as piracy, burglary and treason. In time however the Trevarthian family became both wealthy and outwardly respectable: at the time of his death in 1405 John Trevarthian junior was Sheriff of Cornwall. Despite his appalling criminal record, Penros was sent to Ireland as Lord Chief Justice in 1385. He returned without permission to England the following year and as a result was accused of misconduct. Again he seems to have escaped serious censure, despite his reputation as "a notorious criminal". In 1391 he was appointed a justice of the King's Bench and became justice of South Wales in 1393. He was a trier of petitions in the House of Commons of 1394, but was eventually removed from the Bench on the ground of his record as a notorious criminal. Penros married firstly Joan, daughter of Richard Carnver, who died about 1391, and secondly, in about 1395, Constance, of whom little is known. By Joan he had at least two sons, William and John; John is said to have been an "imbecile from birth". Penros died in 1411.
