“There were only two groups of people who shared Casement’s high opinion of his significance in all of these events,” he said.
Casement himself believed he was a leader arriving to lead his people, while British intelligence services were very interested in him, the Chief Justice said.
Casement had written damning reports on abuses in both the Belgian Congo, and in the Peruvian mining industries, and had been knighted as a result.
Casement was described as an idealist, not a self-seeker, but also extraordinarily vain, the Chief Justice said.
Following his arrest on suspicion of gunrunning at Banna Strand in Co Kerry, Casement was interrogated in the Tower of London, where it was later decided that he should be put on trial.
Casement was one of the 16 men executed because of the Rising, and the only one hanged on English soil, on 3 August 1916, four months after the other leaders.
“The trials that occurred immediately after Easter weekend were trials under the Defence of the Realm Act 1914, and were held in secret, in private, and not in public,” the Chief Justice said.
The Casement trial in London was one of the great set pieces of English law, he added, at which the defendant was represented by several counsel, because of the various treasons acts under which he was charged.
“The trial was not only in public, but it was also one of the great events of that period,” the Chief Justice said.
There are photographs of people queuing to get into the Lord Chief Justice’s court, and tickets were printed, he added.
The trial was attended each day by Casement’s most faithful cousin Gertrude Bannister.
This was in stark contrast to what happened in Dublin, where some of the trials lasted just 15 minutes.
The full majesty of the law was a “designed feature”, the Chief Justice said.
The British government wanted to present the values of fairness and British justice for which it was fighting for in World War One.
This was particularly aimed at the still-neutral United States.
No right of appeal
The Casement trial also carried the right of appeal, unlike the trials in Dublin where there was no appeal, the Chief Justice said.
The trial was also captured magnificently in a brilliant painting by Sir John Lavery, which now hangs in the King's Inns, the Chief Justice added.
Lavery was sympathetic to the Irish Nationalist cause, and left a fantastic historical record, because he painted every one of the people involved in the Treaty negotiations.
The artwork is also unusual in that it is painted from the perspective of the jury box, thus asking the viewers, on some level, to judge Casement and act as jury.
“The sympathy of the artist is pretty obvious in the way he puts Casement in the dead centre of the painting,” the Chief Justice said.
Casement was both handsome and intelligent, and has fascinated people ever since, Chief Justice O'Donnell said.
He captured the imagination of at least three Nobel laureates. George Bernard Shaw petitioned for clemency, while WB Yeats wrote more than one poem about him.
Peruvian laureate Mario Vargas Llosa also wrote The Dream of the Celt, which is a novelistic account of the life of Roger Casement.
That writer spoke in Dublin of his astonishment that there was not a greater memorial of Casement either in Peru or the Congo, the Chief Justice said.
The Nobel laureate also came to the Kings’ Inns to look at the painting of the trial by Lavery.
The fact that Casement was not only gay, but also left graphic diaries recounting his encounters, has added to the endless interest in him, the Chief Justice said.
In his famous speech from the dock, Casement spoke of a judicial assassination and referred disparagingly to lawyers in general.
There was still a view of the trial as the British machine being used in what was not a fair fight, the Chief Justice said.
The lawyers who weren’t at the trial were very distinguished, he noted, and many of them refused the brief.
Chief Justice O’Donnell’s talk may be viewed here.