When arresting a person police must?

Answer 1

Before arresting somebody a Police Officer must give the suspect a caution. Here is the Police Caution in the UK:

"You do not have to say anything, but it may harm your defence if you do not mention when questioned, something which you later rely on in court. Anything you do say may be given in evidence."

Then the officer asks, "Do you understand?" The caution differs in different countries, but is based around the same kind of message.

Added: (in the US) First: The officer must be identifiable as such (by uniform, or other means) and, by their verbal command or actions, convey to the arrestee that they are under arrest and not free to leave.

Contrary to popular belief the arrestee need NOT be advised of their Miranda rights at the time of their arrest (although it usually is done then). This warning is only required to be given before the start of any interrogation relative to the crime for which they have been taken into custody.

Example: If a uniformed officer comes to your house - serves an arrest warrant - slaps the cuffs on you - places you in the back of his car - transports you to the station - turns you over to detectives - and never asks you anything about WHY you are being locked up - you have NOT been unlawfully arrested simply because he did not Mirandize you.

Answer 2

have probable cause to believe the person is involved in criminal activity.