"They can arrest you before you've even THOUGHT of committing a crime." You arrest (halt people from continuing in their normal activity) in order to determine

"They can arrest you before you've even THOUGHT of committing a crime." You arrest (halt people from continuing in their normal activity) in order to determine if a crime has been committed or to determine if the person halted is prima facie guilty and accessory or privy to information about a known crime. It's almost a truism that the police should arrest those who are not able to be proven guilty or are not guilty of any crime. When I've been stopped, yes it makes me nervous, but it also affirms to me that the police are actually taking part in tracing criminals and attempting to reduce crime.