Was he under section????

[Unregistered]

"Was he under section?"


In a British crime drama, two police officers are talking about a mentally ill patient being a resident at a mental hospital when one of them asks the question, "Was he under section?"

What does that mean??

Seems there are a lot of British expressions I can't quite understand
or even find on the internet. It's so frustrating.

Can anyone help? It'd be really appreciated!!!!!!!
Thanks in advance.

[Mister Micawber]

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Was the phrase followed by a cardinal number?
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