To answer these questions he analyses s16 of the MCA 2005, the accompanying Code of Practice and the relevant case law including G v E and Watt v ABC. As a result he dismisses the arguments from the appellants that sought to portray the current law as
"either contradictory or confused. As I have sought to illustrate it has evolved and refined as the Court has been required to address the challenging and diverse issues that have come before it. It is also discernible that the Court is gradually and increasingly understanding its responsibility to draw back from a risk averse instinct to protect P and to keep sight of the fundamental responsibility to empower P and to promote his or her autonomy" 
He then lists eleven principles that emerge from the judgment that can be summarised as follows:
1) The starting point in evaluating any application for appointment of a PWD is by reference to the clear wording of the MCA 2005.
2) "Whilst there is no special alchemy that confers adulthood on a child on his or her 18th birthday, it nevertheless marks a transition to an altered legal status, which carries both rights and responsibilities. It is predicated on respect for autonomy. ....... the imposition of a legal framework which is overly protective risks inhibiting personal development and may fail properly to nurture individual potential. "
3) The structure of the Act and the factors to be considered under Section 4 may well mean that in the majority of cases it is not in the best interests of P for the Court to appoint a PWD.
4) This does not mean there is a statutory bias or presumption against appointment but just "the likely consequence of the application of the relevant factors to the individual circumstances of the case."
5) An 'artificial impediment' to the appointment of a PWD fails to have proper regard to the 'unvarnished words' of the MCA 2005 and would compromise a fair balancing of the Article 6 and Article 8 Convention Rights.
f) The Code of Practice is not a statute but is there to aid interpretation so is not determinative.
g) The same prevailing ethos of the MCA, which is to "weigh and balance the many competing factors that will illuminate decision making" should be applied to the decision to appoint a PWD.
h) The only presumption in the MCA is that set out at Section 1 (2) 'a person must be assumed to have capacity unless it is established that he lacks capacity' and the "recognition of the importance of human autonomy is the defining principle of the Act. It casts light in to every corner of this legislation"
i) P's wishes and feelings and those other factors contemplated by Section 4 (6) MCA will, where they can be reasonably ascertained, require to be considered. None is determinative and the weight to be applied will vary from case to case in determining where P's best interests lie (PW V Chelsea and Westminster Hospital NHS Foundation Trust and Others  EWCA Civ 1067);
j) the framework of the MCA makes the point that appointment of a PWD is not to be viewed as a "less restrictive option than the collaborative and informal decision taking prescribed by Section 5"
k) The wording of the Code of Practice at 8.38 should not be regarded as the starting point as it reflects the likely outcome and should be revisited.
Read the full judgment on Bailii.