If Gerry Adams’ questioning remains just that and does not lead to charges, what are the implications?

Could it give a useful jolt to the negotiations between the Northern Ireland parties to move to an agreed process for dealing with the past?

There have been discussions since the talks led by Richard Haas and the parties are due to resume them after the European Parliament elections later this month. Some have seen encouraging signs of progress.

Some might argue that Gerry Adams’ language last night – “I do not disassociate myself from the IRA and I never will” – was a nuanced move towards more openness.

01 adams1 r w The implications of Gerry Adams arrest

Sinn Fein spokespeople today deny that, but many who interviewed Gerry Adams over many years think they’re hearing movement in that phrasing.

Will it have any effect on the European Parliament elections?

Sinn Fein elected representatives north and south of the border are saying it’s all a plot to undermine their efforts in those elections. It’s hard to imagine it would have any effect on their core vote. Just possible it could on some first time Sinn Fein supporters in Ireland where they have a chance of getting a seat in each of the four regions.

It was Gerry Adams himself who offered himself up for questioning in March.

Read more: Gerry Adams remains in custody over 1972 murder

His own solicitor was in touch with the PSNI beforehand and his statement to RTE on camera last night, pointedly given in front of the Dail where he leads the Sinn Fein team of TDs, did not go for the PSNI, an institution he helped to shape as successor to the RUC.

There was nothing in his words yesterday to suggest he saw this as a breach of the agreements, an act of bad faith, a trigger to a full-scale crisis.

But what happens if he is charged would be a completely different story.

It might be an unlikely hypothetical. There have long been suggestions that the transcripts sitting in the University of Boston safes of interviews with former IRA (and other paramilitary group) members would not be sufficient for prosecutions.

But if they were, under the terms of the Good Friday Agreement and subsequent side deals there is no exemption for a former paramilitary from a fresh prosecution.

If it happened, if the leader of Sinn Fein were charged with anything in connection with a murder, the convulsion to Northern Ireland politics would be immense. He rejects all allegations of involvement.

Michael McConville, one of Jean McConville’s sons, told RTE Radio 1 this morning that back in 1972 between 10 and 12 IRA members came into his home when he and six of his siblings were with his mother. Some of those abductors were masked, some not. He said he recognised three or four of them as neighbours, his elder siblings recognised more.

Jean McConville’s purse and family rings were later left with the family by an IRA member. It was then, Michael McConville said on RTE’s “John Murray Show,” he knew he’d lost her. He said some of his mother’s original attackers still look him straight in the face as he passes them in the street.

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