R (AA (Afghanistan)) v Home Secretary
 UKSC 49,  1 WLR 2224
The appellant claimed to be a child, but a local authority assessed him to be an adult. The Home Secretary acted on the basis of that assessment and detained him for removal. Later, a different local authority assessed him to be a child. Had the Home Secretary’s duty under section 55 of the Borders, Citizenship and Immigration Act 2009 regarding the need to safeguard and promote the welfare of children been breached when he was detained, so as to make his detention unlawful?