Rebekah Brooks, the former chief executive at Rupert Murdoch’s News International, was said to be arrested on Tuesday morning in connection with the phone-hacking scandal that plagued the News of the World and the Sun. It was the second time Brooks was arrested in the case, though she was previously released. In fact, more than 40 people have been arrested amid the investigation, but so far none of them has been charged. Why do British police keep arresting people and then releasing them?

Because it’s a lot easier to arrest someone in the United Kingdom, but being arrested there isn’t a big deal like it is in the United States. American police need probable cause to make an arrest, but in the United Kingdom, officers can arrest on suspicion. Probable cause is defined as the belief that a crime was probably committed, and that the suspect was probably responsible. Reasonable suspicion means that a right-minded individual would have grounds to suspect that a crime had been committed and that the suspect might be responsible. To have probable cause, greater evidence is required.

Being arrested on suspicion in the U.K. isn’t so unpleasant as being arrested in the U.S. In fact, you’re likely to be released within hours without paying any bail. First, a British police officer reads the offense you’re suspected of and then your rights. Your rights are not exactly the same as your Miranda rights in the U.S., but they similarly include things like the right to remain silent. (However, in the U.K. your silence may be used against you under certain circumstances.)”* You won’t be told that you have “the right to an attorney,” but you do have right to a “solicitor” who will represent you in court the same way. A proper British officer will read these aloud from a document rather than cite them from memory. (U.S. officers are told to do the same.) After you’re handcuffed you’re taken to the nearest local police station, usually in a police van or panda car. (These were once white and black or white and blue, but now they’re often checkered blue and yellow.)

Once in the station, usually only suspects who appear dangerous or drunk or just a nuisance are locked up. Even those who are locked up won’t have to share a holding cell (in some parts of the U.S., holding cells can contain several people at once), and some officers have observed that the U.K. cells tend to be cleaner. British police next will conduct an interrogation (the preferred term is “interview”), which is recorded on audio or videotape. Finally, the suspect is let out on bail, which is a temporary release that often costs nothing, depending on the severity of the offense and the likelihood a suspect would flee. The same rules apply in all of England and Wales—unlike in the U.S., where many laws vary from state to state—but the criminal-justice systems in Scotland and Northern Ireland are different.

Those who are let out on bail may not be totally off the hook. British police continue to collect evidence, and as soon as they have enough evidence to charge, they are required to arrest again and charge. At that point the suspect will go before a magistrate, who determines whether the he or she must be detained further, or whether he or she can again be let out on bail again.

While the U.S. criminal justice system differs from the British system in a few key ways, it’s based largely on British principles. The American legal system was modeled on British common law, which had been in effect for hundreds of years before the American Revolution. Our policing system, on the other hand, is based on the model of Sir Robert Peel (from whom the British slang for officers—bobbies—originates). Peel created the Metropolitan Police Service in London in 1829, establishing a police force of ranked officers in uniform. Early U.S. police forces, such as the Boston Police Department, established in 1838, and the New York City Police Department, established in 1844, followed Peel’s lead.

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Explainer thanks John Borland of the University of Chester, Carol Jones of the University of Gloucestershire, and Ross Wolf of the University of Central Florida.

Clarification, March 21, 2012: This paragraph was revised to make clear that in the U.K. your silence may be used against you in some limited cases. (Return to the updated sentence.)