An independent review into concerns about police surveillance of journalists, lawyers and other groups in Northern Ireland is set to be published.
The McCullough Review has examined the use of surveillance by the Police Service of Northern Ireland (PSNI) against certain groups and people between 2011 and last November.
They include journalists, lawyers and non-governmental organisations (NGOs) as well as regulators, including the Police Ombudsman for Northern Ireland and the Northern Ireland Policing Board.
The PSNI has come under pressure following remarks that the use of such surveillance breached the principles of press freedom and legal privilege.
As a result, the Chief Constable of the PSNI, Jon Boutcher last year asked Angus McCullough KC to carry out an independent review in the public interest, and with the aim of enhancing public confidence in policing in Northern Ireland.
Mr McCullough, a senior barrister based in London, has said he has been afforded full access to PSNI records, systems and serving personnel to carry out the review.
He has also said that no person, whether from within the PSNI or outside of the organisation, has refused to engage with his review.
Mr McCullough received a total of 55 submissions in response to his appeal for evidence, the majority of which have been from journalists and lawyers.
In a progress report published in January, Mr McCullough said that the majority of his initial work related to identifying and understanding the various systems used by PSNI over the 14-year period under review to store documents authorising different types of covert surveillance, and the resulting intelligence arising from that surveillance.
"We have also been keen to understand the scope, on a theoretical level, that there may be for bypassing the proper statutory processes, and any vulnerabilities in the systems. That understanding informs consideration of the likelihood of 'off the books' surveillance and how that might be detected," the report stated.
"The potential for this varies considerably, depending on the type of surveillance under consideration.
"We have also had in mind that surveillance may not necessarily be targeted against someone of ‘special status’ in order for it to have a relevant impact - such as tending to reveal legally privileged or journalistic material, including journalistic sources."
Journalists, lawyers and other groups are deemed to have "special status" under surveillance legislation arising from material disclosed in ongoing Investigatory Powers Tribunal (IPT) proceedings.
Last December, the IPT ruled that a covert surveillance operation authorised by a Northern Ireland police chief in a bid to unmask a journalistic source was unlawful.
The tribunal quashed the decision, made by former PSNI chief constable, George Hamilton, to approve the Directed Surveillance Authorisation (DSA) in an investigation into the leaking of a confidential document that appeared in a documentary on a Troubles massacre.
Mr Boutcher took over as Chief Constable of the PSNI in November 2023.
Earlier this year, he referred allegations that the force spied on a journalist working on a documentary about the death of a teenage schoolboy in Northern Ireland to the McCullough Review.
The PSNI has denied the claims, and also rejected a suggestion that it may have been behind a break-in to a car belonging to Donal MacIntyre at Heathrow Airport in October 2024.
At the time, Mr MacIntyre was working on a book and a crowd-funded documentary about the death of 14-year-old Noah Donohoe.

Mr Kearney, who is now RTÉ's Northern Editor, worked for the BBC at the time as Home Affairs Correspondent.
Last year, the BBC wrote to the IPT about alleged PSNI surveillance of phone data linked to Mr Kearney’s work at the time.
However, the McCullough Review report published today will not include any matters relating to ongoing proceedings before the IPT and therefore, Mr Kearney’s case will not be referred to in the document, which is expected to be around 200 pages in length.
The chief constable, Mr Boutcher will publish the main report drafted by the McCullough Review - including its findings and recommendations this morning.
A group of experts and stakeholders was also previously formed to advise and provide direction to the review.
Its members include: Human Rights Advisor to the Northern Ireland Policing Board, John Wadham; the first police ombudsman for Northern Ireland, Nuala O’Loan; and barrister and human rights campaigner, Martha Spurrier.
The group also includes representatives from the following bodies: Amnesty International UK; the National Union of Journalists (NUJ); the Northern Ireland Human Rights Commission; the Law Society of Northern Ireland; and the Committee on the Administration of Justice Northern Ireland.