Apparently in the UK it is an offence to refuse to remove a face covering if asked by police who believe a crime may be committed. What is the threshold for this belief, and how does the crime have to relate to the individual who must take off their face covering?
The example today is the news that masked men appeared in the public gallery of a Belfast court during a murder trial.
Another example, where the request was made to remove the face covering was made and reason was given, is documented by John Oliver (youtube). Here someone is required to remove their face covering and eventually fined £90, though it is not clear what that is for. The audio is somewhat mumbled, for this question assume they say (conversation 6:00):
Public: What is your suspicion?
Police: The fact that he walked past a clearly marked camera and covered his face
In both these cases one could certainly argue there is reason for suspicion, in the english language sense of the word. However, it is not at all clear what specific crime may be committed or by whom. If the sole fact that one chooses not to show ones face in a public place is enough to justify the request to expose one's face, then it is effectively the same as an unqualified right and the police can ask anyone to expose their face.
What is the threshold to allow the police to require you remove a face covering? Can we say how close these examples are to that threshold, and what aspects would be considered? How specific does the link between the crime and the individual have to be? Is there any procedure that must be used before it is a legal requirement to remove a face covering?
The examples take place in Northern Ireland and England, answers for any or all of the home countries would be interesting, as they would for any other jurisdiction.