Public Interest Immunity

[brianixon]

Does anyone have any knowledge or history of dealing with the police when they cite this as a reason for not giving a reason for their actions?
Friends are a risk of police creating a case law precedent and being powerless to challenge.
Or can you recommend where I look rather than Google and random links?

Public interest immunity allows the Crown (police, CPS) to withhold evidence that would normally have to be disclosed to a defendant because it helps their case and/or undermines the prosecution's case. The prosecution applies to the court for PII. If it is granted, the defence can challenge that decision.

If your friend has a solicitor working on their defence, they should be able to advise.

Thanks @prh47bridge, yes they have solicitors I am not looking to advise them. I would like to find about the system and try and understand it. Everybody around this case seems to be shrugging their shoulders. Solicitor understands and has challenged a couple of things. Nobody else seems to have a clue. Was it designed for serious cases like National Security?
This isn't a case like that. Ordinary coppers not Secret Service.

It isn't just about national security. It can also apply to protect journalists' sources, material relating to children, police informers, police observation posts, police reports, police manual, police methods. This is not an exhaustive list.