Prominent Catholic clergyman Monsignor Denis Faul has died at the age of 74 following a long illness.
He first came to prominence in 1969 when he spoke out against the judiciary, claiming Catholics felt judges were biased against them.
While he campaigned against the ill-treatment of prisoners, he also was an outspoken critic of IRA violence.
Archbishop Sean Brady said he "stood up for what he believed in, for the distraught" regardless of background.
"With valour and hope he unstintingly gave his advice, assistance and support, never counting the cost or risk to himself," the Catholic Primate of Ireland said.
"He realised clearly that justice is not a casual by-product of peace, but something anterior and fundamental to any lasting peace.
"His whole life was an eloquent testimony that justice requires consistent courage, and that peace must be underpinned by morality at all times."
A teacher for more than 40 years, many of which were spent at St Patrick's Academy in Dungannon, Monsignor Faul was renowned for his outspoken views.
He was Catholic chaplain at the Maze prison during the H-Block hunger strikes in 1980 and 1981.
While he strongly opposed the fasts, he also urged the government to introduce prison reform to defuse the crisis.
Monsignor Faul was a teacher for more than 40 years
His efforts in organising meetings of the hunger strikers' families was viewed as instrumental in bringing the protest to an end.
Back in 1969, his criticism of the judiciary in 1969 brought him a rebuke from the then-Catholic Primate of Ireland, Cardinal Conway.
He was strongly critical of the Army and the RUC, while also condemning the Provisional IRA.
In March 1977, he described the IRA campaign as spurious and directly contrary to Catholic teaching.