An Garda Síochána has been dogged by a series of scandals over the last number of months.
Last year Ms O'Sullivan was forced to deny claims she instructed her legal team to discredit Garda Sergeant maurice McCabe at the O'Higgins Commission which was set up to investigate allegations of misconduct in the Cavan-Monaghan district.
Enda Kenny (centre) with Richard Bruton, Simon Harris, Paschal Donohoe, Leo Varadkar, Frances Fitzgerald and Michael Noonan at an election news conference. Photo: Tom Burke
And earlier this year that controversy erupted again when it was claimed by former garda Press Officer David Taylor that he was instructed by the Commissioner to engage in a smear campaign against Sgt McCabe.
Recently questions have been raised after Ms O'Sullivan appointed some of her closest allies, who had retired from the force, to the internal unit tasked with liaising with the tribunal into the Garda Whistleblower scandal chaired by Mr Justice Peter Charleton.
What is the latest scandal all about?
Last Thursday at a garda press conference it was announced that 14,700 people were wrongly convicted of motoring offences after they weren't given the opportunity to pay a Fixed Charge Notice.
Gardaí also confirmed that almost one million phantom breath tests were recorded on the Garda Pulse system. Official figures claimed that 1,995,369 tests were carried out but only 1,061,381 took place.
A large bill for compensating people who were wrongly brought to court is likely to be footed by the taxpayer.
How did the Commissioner respond?
On Monday Ms O'Sullivan staged a press conference in Garda headquarters where Noirin O'Sullivan she apologised and promised "real cultural reform". She warned that it won't be easy and will take time.
Speaking on RTÉ's Six One news, Ms O'Sullivan later said: "I have a huge commitment to the programme of reform that I have committed to undertake. It is working and it will continue. Not everyone is going to like it and we are going to have some serious push back but it takes determination, it takes commitment and courage to make sure it happens."
The Commissioner said she wouldn't step down, even if there was a vote of no confidence in her in the Dáil
However Justice Minister Frances Fitzgerald has strongly defended the Commissioner. She has been backed up by the Taoiseach.
In the Dáil last night, Ms Fitzgerald said Ms O'Sullivan is the best person to lead the force.
However, Ms Fitzgerald says she was unaware of the scale of the latest crisis in the Gardaí until last week.
But at the cabinet meeting a major stand-off took place with Ministers asking "What's next?"
Finance Minister Michael Noonan and several other Fine Gael ministers warned the latest controversies were sapping public confidence in the force.
Ministers directly challenged Tánaiste Frances Fitzgerald on the controversies, demanding to know: "What's next?"
At one point at the "emotional" meeting, Jobs Minister Mary Mitchell O'Connor raised the prospect of a "straw poll" of ministers to determine the level of confidence in Ms O'Sullivan.
Arts Minister Heather Humphreys also voiced serious concern about the garda scandal. No such poll was held, but a Cabinet source said: "The level of anger and hostility towards the gardaí was palpable."