When i wrote about this issue last week, i raised - albeit slightly tongue in cheek - the question of carrying out a citizen's arrest. i said then, echoing advice from a criminal lawyer, that such a course of action was highly dangerous legally and not something to be advised lightly.
a police officer attempting to detain someone unlawfully may be carrying out an act of unlawful detention. That is a criminal offence and for that, they could be arrested.
However, when it comes to carrying out an arrest, there is a very clear distinction between the arrest powers with which the police are endowed and the powers with which an ordinary member of the public is endowed. For the police to arrest someone they need only reasonable grounds for so doing.
Suspicion that someone has just committed a crime are reasonable grounds, so police officers may arrest on suspicion.
The ordinary member of the public can only arrest where the crime in question has actually been committed. How do you know its been committed? When a court says it has. Therefore, even if you saw someone removing goods from a shop and making off thru the door with them, be very careful. They MIGHT have merely forgotten to pay...in which case, whilst a police constable can validly carry out an arrest in such circs, any arrest YOU carry out would be unlawful detention and chances are YOU would end up in the dock.
Worse: case law contains various examples of the consequences of someone making an unlawful arrest. Individuals are entitled to resist unlawful arrests/detentions - and that resistance may include some degree of violence.
Yes. That applies to the police too...but how sure would you be that after the event, you can prove that you resisted an unlawful s44 arrest and therefore hit the police officer lawfully...as against the polcie story that you hit them and they then arrested you for assault? You'd need clear video recordings of the event, plus some good credible witnesses.
Other slight prob with making a citizen's arrest: the offence must be punishable by a sentence of at least five years. How well do you know your sentences? If you see a crime being committed, is the max penalty 5 years? 10? 3?
Get it wrong, and your citizen's arrest fails and opens you to all the consequences noted above.
So yes. As thought excperiment, arresting a police officer makes for an amusing scenario. As practical course of conduct, it just ain't.