P v Cheshire West and Chester Council  UKSC 19 and press summary. The Supreme Court's judgment has provoked considerable discussion - for example, Royal College of Psychiatrists and Justice Gap - A gilded Cage is still a Cage. The key feature of deprivation of liberty is, according to the Supreme Court, whether the person is under continuous supervision and control and is not free to leave. The court added that the person's compliance or lack of objection, the relative normality of the placement and the purpose behind it are all irrelevant to this objective question.
One major consequence of the Cheshire West decision was
that the number of Deprivation of Liberty applications increased markedly as Local Authorities took a cautious approach and sought court approval. The practical application of the test has also proved to be difficult as illustrated by Rochdale MBC v KW  EWCOP 13 Mostyn J. In a further case, Bournemouth Borough Council v PS and DS  EWCOP 39, Mostyn J has called for the Supreme Court to review the Cheshire West decision.
Parliament has stated that in the Mental Capacity Act 2005, references to deprivation of liberty have the same meaning as in Article 5(1) of the European Convention on Human Rights - see MCA 2005 s64(5). However, it may be that "deprivation of liberty" is not capable of precise
definition since the actual facts of cases vary considerably. Is it something that you cannot define but you know it when you see it. As Mostyn J put it in the Bournemouth case (para 29):
Ultimately I think that whether a factual situation does or does not
satisfy the acid test is likely to be determined by the "I know it when I
see it" legal technique. That received its most famous expression from
Justice Potter Stewart in the US Supreme Court in Jacobellis v Ohio (1964) 378 U.S. 184, an obscenity case, where he stated "I shall not
today attempt further to define the kinds of material I understand to be
embraced within that shorthand description [of hard-core pornography];
and perhaps I could never succeed in intelligibly doing so. But I know
it when I see it, and the motion picture involved in this case is not
that." The technique has been expressed in zoological metaphor. In Cadogan Estates Ltd v Morris  EWCA Civ 1671,
a case about a claim for a new lease, Stuart-Smith LJ stated at para 17
"this seems to me to be an application of the well known elephant test.
It is difficult to describe, but you know it when you see it". Another
expression is the well known aphorism attributed to the American poet
James Whitcomb Riley who wrote "when I see a bird that walks like a duck
and swims like a duck and quacks like a duck, I call that bird a duck"
Mostyn J concluded his judgment in the Bournemouth case by stating:
I do not criticise this local authority in the
slightest for bringing this case. In the light of the decision of the
Supreme Court local authorities have to err on the side of caution and
bring every case, however borderline, before the court. For if they do
not, and a case is later found to be one of deprivation of liberty,
there may be heavy damages claims (and lawyers' costs) to pay. I remain
of the view that the matter needs to be urgently reconsidered by the
New Law Journal 7th May 2015 -Liberate social policy from the influence of Human Right, says Jon Holbrook
Thinking legally 18th June 2015 - Deprivation of Liberty safeguards descend into costly chaos