Bullying: The Irish lawyer investigating Carwyn Jones

James Hamilton has begun investigating whether Carwyn Jones misled the assembly

The fate of Wales' first minister could rest in the hands of an Irish lawyer who was once his country's top prosecutor. Now he will decide whether Carwyn Jones broke the Welsh Government's code of conduct. BBC Wales political correspondent Daniel Davies profiles James Hamilton.

The allegation is serious: that the first minister misled the assembly when he said that no one at the top of his government had complained about bullying.

In other words, he's accused of lying. Ministers found to have done so are expected to resign.

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Mr Jones denies breaching the code.

But since dismissing the late Carl Sargeant - an alleged victim of bullying - he has faced intense pressure, of the kind he has not experienced since taking the reins in 2009.

He wants to prove he did nothing wrong and has nothing to hide, hence the invitation to Mr Hamilton to examine the evidence and publish his verdict in a report.

A thumbs-down from James Hamilton is likely to make Carwyn Jones' position untenable

Although Mr Hamilton cannot sack the first minister, a thumbs-down would surely make Mr Jones's position untenable.

Born in Dublin in 1949, James Hamilton started practising as a barrister in 1973 and later worked for Ireland's attorney general.

As a high-ranking civil servant, he saw first-hand how the law can play a role in political controversies.

When Mr Hamilton worked there, the attorney general's office became embroiled in the landmark "X Case" about whether a young girl should be allowed an abortion in the UK.

Another scandal, involving the extradition of a paedophile priest, brought down a coalition government.

Prof Carol Coulter, of National University Ireland Galway law school and a former legal affairs editor of the Irish Times, says Mr Hamilton earned a reputation for being "very independent and very tough-minded".

"As was revealed in the controversy around the attorney general's office, when he had to face a parliamentary inquiry, there was never any question of him being able to deal with all of the politicians and to maintain the independence of his role as a public servant," she says.

"So I don't think he's likely to be susceptible to any kind of pressure."

In 1999 he was appointed director of public prosecutions, the Irish equivalent to the head of England and Wales's Crown Prosecution Service. As the man in charge of all prosecutions for the state, the job came with a public profile.

James Hamilton served as Irish Director of Public Prosecutions until 2011

Until 2013, he was also president of the International Association of Prosecutors, based in The Hague.

In the same year, he became an independent adviser to the Scottish Government on its ministerial code, the same role he now takes on for the Welsh Government. He has not, however, submitted any advice since being appointed in Scotland.

Mr Hamilton, or Jim to his friends, steps into Welsh politics after a tumultuous few weeks. But Ms Coulter says he will not be fazed.

We do not know who he will talk to in the course of his work or how long he will take. The scope, deadline and format of the inquiry are matters for him to decide, the government says. He started his investigation this week.

Conservatives still have concerns about whether the process will get to the truth. They wanted a committee of AMs to investigate, but Labour says such a committee could never demonstrate the impartiality required.

Instead, Mr Jones has copied from the Scottish Government's code and borrowed its adviser.

Whatever and whenever Mr Hamilton publishes, every word he types will be pored over.