We now understand what the highest Catholic authority in the land regards as an adequate moral defence against the charge of colluding with a paedophile priest against the state.
For what absolves Cardinal Brady, in his own mind, is what he must concede absolves all below him who behaved as he did.
When deployed by his bishop to witness a pledge of silence from the victims of the odious Brendan Smyth - the most notorious of all the paedophile priests because his outing was the first major one in a long series since - Fr Brady, as he then was, did what most other priests would have done at the time.
He was just obeying orders.
A priest makes a pledge of full obedience to his bishop at ordination. There are now serious grounds for considering whether that pledge should be allowed in law.
Cardinal Brady explains that there were people in authority over him who were properly appointed to make the kind of decision that he, as a bishop's flunky, could not make.
There were no procedures in place by which a mere priest could act against the wishes of a bishop to report the rape of children to the police and to report his own seniors for exacting secrecy from the victims.
Well, no doubt there weren't.
A priest was not an independent citizen with a responsibility to deal directly with the institutions of the state.
And the church of that time lived in the smug confidence that its authority was higher than that of the law of the land.
So, what Cardinal Brady says in his defence merely confirms the most negative perception of the church he now heads; that it was a law onto itself and that those who lived by that understanding are even yet immune to criticism for having surrendered their civic duty and their moral consciences.
If the Cardinal does not withdraw this defence, then he allows it to countless other priests and bishops who, in the past, lived by the precept that they were above the law and that they had a right to conceal paedophilia from the police.
And he misses the significance of the disclosures of the past year.
The Murphy and Ryan reports into abuse by clergy and members of religious orders, and their cover-ups, didn't go in much for retrospective justification.
And heads rolled in some dioceses at least, as bishops recognised that their moral authority was tainted by their participation in cover-up.
If Cardinal Brady does not step down then he is saying, in effect, that these others need not have stepped down either.
And even if there is a legal clause that allows that he did not break the law when he witnessed cover-up and did not speak out, their is no moral defence.
And Cardinal Brady's misfortune is that he must be a moral exemplar - and he is not.
He has known, throughout the agonising in this country after the Murphy report, that he was as vulnerable as any other priest to the charge of collusion.
And if he was really leading the new open church he promised, then he should have stated frankly at that time that he had himself worked on cover-up procedures and asked the forgiveness and indulgence of his flock.
It is an extraordinary reflection on his church that it elevated him to the post of Cardinal without checking - or perhaps without caring - that past scandal might rise up to undermine him.
Certainly, he could not run for public office in any other organsation if his colleagues knew that he had once taken statements from abused children in which they pledged themselves to secrecy.
What did his fellow bishops know? This case has been brewing for years. What did the Pope know?
Did the Pope, when he summoned bishops to Rome last month, know that the Irish Primate himself, a cardinal, was vulnerable to being outed in this way?
What is needed of Cardinal Brady is that he can stand above any scandal that arises and that he can make clear the church's total rejection of paedophilia and cover-up. He can not now do that.
He must never be vulnerable to having any other colluder point him out as a reason to evade resignation.
Yet, if he does not go, then many of the others who will be exposed in future will be able to refuse also to go.
And if his defence remains that he was only doing what any other priest in his position would have done at that time, then every priest in the country must come under suspicion of having done the same.
There were some in the church who believed that the worst of the scandals was over, with the sample cases examined and exposed by the Murphy and Ryan reports.
But Cardinal Brady's defence of his action carries the implication that the whole church was primed to collude against victims and against the law.
If that is the case, then the whole church should be investigated; every diocese. Flush them all out.