O'Brien's resignation followed publication of allegations that he had engaged in inappropriate and predatory sexual conduct with priests and seminarians under his jurisdiction and abused his power.

His studies for the priesthood were at St Andrew's College, Drygrange, Roxburghshire, and he was ordained priest on 3 April 1965 by his predecessor, Cardinal Gordon Gray.

Initially serving as curate at Holy Cross, Edinburgh from 1965 until 1966, he completed his teacher training certificate at Moray House College of Education.

Professor Manfredi La Manna wrote, "I, for one, would not recognise as a colleague someone who admitted abusing his position of power for sexual gratification with subordinates.

"[7][8] The university decided against this, noting, "(...) that revocation cannot change or ameliorate the wrongs of the past and that, notwithstanding the very real hurt and loss caused by the actions of the honorand, it would be no more than an empty gesture.

[citation needed] O'Brien said he did not know; Nichols said English, Welsh and Scottish bishops had "robust" rules in place to protect children.

[11] Mario Conti, Archbishop emeritus of Glasgow, said all the Scottish Catholic bishops except O'Brien cooperated over an independent inquiry into the handling of child abuse in Scotland between 1952 and 2012 with the results to be published.

[20] On 24 February 2013 he did not attend a special service to celebrate the eight-year tenure of Pope Benedict XVI at St Mary's Cathedral, Edinburgh.

[21] On 25 February 2013 it was announced that O'Brien's previously submitted resignation as archbishop would take effect that same day, and a temporary apostolic administrator was appointed in his place.

On 3 March 2013, the Scottish Catholic Media Office released a statement from O'Brien in which he said, "I [...] admit that there have been times that my sexual conduct has fallen below the standards expected of me as a priest, archbishop and cardinal.

[26] One of the four whistleblowers who testified against O'Brien in 2013, Brian Devlin, who later left the priesthood, in 2021 waived anonymity to publish a book, Cardinal Sin, about his experiences and his fight for improved church governance and accountability.

[33][34] In 2015, The Glasgow Herald reported allegations that in at least 40 cases young clerics were encouraged to let O'Brien hear their confessions, and the religious act was used for sexual grooming.

[37] On 27 April 2013, The Scotsman reported that Cardinal Marc Ouellet would head an investigation into O'Brien, and that appointment of Scottish bishops had been halted until the inquiry was completed.

But in the past, wayward priests have been sanctioned by the Vatican with punishments of 'prayer and penance', and the statement made clear Francis supported the move and that the Holy See would decide his future fate.

Richard Holloway, former Bishop of Edinburgh in the Scottish Episcopal Church, said that forcing O'Brien into exile from Scotland would breach international law.

Holloway likened O'Brien's forced exile to the tactics of "extraordinary rendition" (extrajudicial transfer) of the US Central Intelligence Agency (CIA).

According to Peter Kearney, the director of communications of the Catholic media office (which was largely unavailable for official comment), only Rome could handle the O'Brien affair; nobody in Scotland had authority to challenge a cardinal.

[2] According to Catherine Deveney writing in The Observer, Archbishop Tartaglia, who was temporary leader of St Andrews and Edinburgh following O'Brien's resignation, failed to confront the issue, and behind the scenes "church insiders" were critical; one told her that "He is completely lacking in leadership qualities".

[52][53] According to the article, senior figures in Rome said the visitation would also deal with the more general accusations of moral failings in the church in Scotland.

[56] O'Brien had since January 2014 been living, initially incognito, in a home provided by the Catholic Church[57] in the village of Ellington, Northumberland, fifty miles south of the Scottish border.

[69] O'Brien suffered from heart problems and was fitted with a pacemaker after complaining of dizzy spells and fainting prior to Passion Sunday Mass in March 2008.

Referring to equality legislation which prevents discrimination against homosexuals, he [O'Brien] said Christians faced being sidelined in British society because they were not willing to publicly endorse lifestyles that run contrary to their belief system.

[76]His [O'Brien's Easter 2011] homily included instances where Christians had fallen foul of equality legislation, preventing discrimination against gay people, and swiftly drew fire from groups campaigning against religious privilege in public life.

"[81] In January 2006 he criticised Westminster MPs over the introduction of civil partnerships in the UK, and Holyrood members over the liberalisation of divorce laws in Scotland.

[82] In July 2006 he opposed proposals to change the law which would require Catholic adoption agencies to place children with homosexuals in the same way as with heterosexuals, calling them totalitarian.

[85] Conservative MP Margot James, who was considered one of the most influential gay women in 2009,[86] called these comments "scaremongering" and said: "I think it is a completely unacceptable way for a prelate to talk.

"[87] Dan Hodges wrote: "I can't remember the last time I read a more morally and intellectually bankrupt rant from a senior member of the clergy.

Some scientists suggested that he intentionally used inflammatory language to stir up opposition to the bill; others argued he was sticking up for morals and forced the Government to allow MPs to vote freely on the issue.

[69] In February 2010, the Secretary of State for Scotland, Jim Murphy, said in the House of Commons that faith was "at the very foundations of the Labour Party" and encouraged openness to religion in public life.

"[97] O'Brien said to the Leader of the Scottish Labour Party, Iain Gray, "I hope he [Pope Benedict XVI] gives you hell [during his September 2010 visit] for what has happened over the past 10 years.