He was born at Killeglan, now Ashbourne, County Meath, son of Richard Segrave, Baron of the Court of Exchequer (Ireland) who was head of a prominent landowning family. He married before 1589 Mary Dillon, daughter of Chief Justice Robert Dillon, who in the latter year sent him to London with gifts of hawks and horses for the Privy Council.
On his father"s death in 1598 Patrick took his place as a Baron of the Exchequer. He was charged in 1602 with bribery and corruption, and stood trial before the Court of Castle Chamber, the Irish equivalent of Star Chamber. The Delahide family"s lands at Dunshaughlin, County Meath had been forfeited by the Delahides to the Crown for treason.
Segrave was accused of conspiring with Richard Read and David Russell to procure a jury to find the title in favour of Read, and of receiving a large bribe in return.
He was also charged with attempting to bribe Sir Richard Cooke, the Chancellor of the Exchequer of Ireland. Segrave was found guilty, removed from office, fined £1000 and imprisoned at the pleasure of the Crown.
He attended meetings of the council until 1610, after which his name disappears from the records.
His disgrace was not permanent. In 1607 he was admitted to the King"s Inns and became a member of its" governing council.
