MHA 1983 s2 allows for up to 28 days of detention for assessment, or assessment followed by treatment.
Where the application is made by an AMHP, he must, before or within a reasonable time after the application, take such steps as are practicable to inform the person (if any) appearing to be the nearest relative of the patient of (i) the application and (ii) the NR's discharge powers (s11(3)).
The section will usually lapse at midnight on the 28th day (e.g. if the section began on a Sunday, it will expire at midnight on a Saturday/Sunday) and cannot be renewed (s2(4)); however
Section 2 is generally used for first admissions. Once someone is known it is more common for them to be admitted under section 3 (admission for treatment).
The patient can be forcibly medicated, and the Consent to Treatment provisions apply (s56).
An emergency admission for assessment can be made under s4.