From Mental Health Law Online
(1) An adult in the exercise of parental responsibility may impose, or may authorise others to impose, restrictions on the liberty of the child. However restrictions so imposed must not in their totality amount to detention. Detention engages the Article 5 rights of the child and a parent may not lawfully detain or authorise the detention of a child. (2) The restrictions authorised by RK's parents did not amount to deprivation of liberty: they were no more than what was reasonably required to protect RK from harming herself or others within her range.
Re RK; RK v BCC (2011) EWCA Civ 1305
RK (by her litigation friend the Official Solicitor) v BCC, YB, AK
Hearing: 12/10/11 - 13/10/11
Before: Thorpe, Gross LJJ; Baron J
Richard Gordon QC and Joseph O'Brien (instructed by Irwin Mitchell LLP) for the appellant
Jonathan Cowen (instructed by BCC) for the First Respondent
David Lock QC and Laura Davidson (acting pro bono instructed by Anthony Collins Solicitors) for the Second and Third respondents.
 All ER (D) 28 (Dec)
Transcript. Transcript revised to contain concurring judgments of Gross and Baron LJJ.
39 Essex Street, 'Court of Protection Newsletter' (issue 16, December 2011). Detailed summary available here