There are different forms of detention, and different forms of forced treatment.

These are described (for England) in the Mental Health Act.

This is what it means to be sectioned - you are detained under section of the mental health act.

The most common sections are:

Section 136: a police officer can detain you in a public place and take you to a place of safety to be assessed. This requires one police officer. It lasts a maximum of 24 hours (but it can be extended by 12 hours).

Section 2: this is a short 28 day hold for assessment and treatment. It requires 2 doctors and an AMHP. Traditionally AMHPs were social workers, but they don't have to be and there are increasing numbers of nurses becoming AMHPs.

Section 3: this is a six month hold for treatment. It requires 2 doctors and an AMHP.

Section 4 is another short term hold (72 hours) that can be used in emergencies if there's only 1 doctor available.

https://www.rethink.org/living-with-mental-illness/mental-he...