Before turning to that decision it is a good reference to read the analysis of M. Travis, May 1998 into the exercise of the RPOM in New Zealand in which it is revealed that the whole concept of the RPOM is fundamentally misunderstood by the Justice Department and it's advisors to the point that it has at times relied upon 'advice' from within the Department as virtually anecdotal reference. In the mean time taken from M. Travis's paper is the fellowing conceptual grasp that McDonald didn't bother with and failed to even reference it seems:
In de Freitas v Benny  (Court of Appeal in Trinidad), Lord Diplock observed that “mercy is not the subject of legal rights [but] begins where legal rights end.” Christopher Gelber considered this a ruling that “the exercise of the prerogative of mercy was inherently extra-legal in nature and therefore not justiciable,” as did Lord Roskill in the G.C.H.Q. case  A.C. 374. Furthermore it cannot be denied that the Crown’s ability to pardon displays the necessary characteristics of a true prerogative; yet there are those like Watkins L.J. who reject the test of justiciability “in favour of an examination of the court’s capacity to weigh the competing issues of principle in each case.” Watkins considered the courts to be competent enough to review the prerogative of mercy.
While the points of view discussed above are regarding the opportunity to seek Judicial Review, an important observation is made by Lord Diplock as to what mercy in fact is in the concept of the RPOM - it starts where Legal rights end. That is where appeals may have been exhausted and there in no other route for a petitioner to take - in practice in New Zealand the venue for a way back to the Courts for fresh evidence, or any evidence going to the safety of a conviction may go back to the Courts. Although the scope is wider than the legislative 'right' to have a case referred to the Courts, that would have been the proper recommendation for McDonald to have made. Immediately upon reading McDonald on the Watson application two clear 'positions' become obvious. Firstly, McDonald does not address, apart from in the barest way what her 'appreciation' of what the RPOM is, normally in a report this would be done at the outset and again in the conclusion. McDonald should have spelt out what her 'job' was and how she understood it should be done, and the way in which it was performed to meet public expectation of the exercise of a Royal Prerogative. In fact she has produced an opinion contrary to not only the concept of Mercy, but contrary to the Law. Reading the text of her report the second erroneous 'position' becomes clear. Also, probably inadvertently, explaining the first 'error' - she reveals her an apparent 'duty' to conduct a trial or review of the application as if she were a Judge in an Appeal Court - but even there, as both the Lundy and Bain Privy Council decisions show, she got it wrong in her 'Judgement.'
There are three striking errors in the McDonald report, even overlooking that no description was given of the RPOM in operation or how the author understood, with references, what the RPOM is in essence. It appears she feels the Royal Prerogative extended to her own whim giving her free reign to act as an omniscient Judge.
# Secret Witness A who reportedly recanted his testimony of a gaol house 'confession' by Watson. Despite all the Government resources behind her, McDonald was unable to locate this Crown witness. As far as I'm aware she never sought the help of The Crown to find him, leaving speculation that the Crown, or McDonald in fact on contract to the Crown, didn't want to find the witness. It remains that The Crown have been 'unable' to locate their own witness, a witness upon whom they relied to gain a conviction. McDonald did not offer that as a discount against Watson's conviction but rather allowed the discount to The Crown who were unable to produce their witness in an attempt to disprove or confirm the recantation. One can only wonder if the Crown already knew their witness was no longer 'pliable' to inducement. That's neither fair nor merciful for a conviction to stand on evidence that has essentially been withdrawn, or put another way - no longer exists. This was not an unimportant witness but one whose evidence went to the heart of Watson's conviction and a person for whom it can be argued 'sold' their evidence to the Crown in order to obtain favourable treatment, evidence which wouldn't have been admitted in some other jurisdictions.
# McDonald never once tested the totality of the weakened aspects of the Crown case against the conviction. Of course that wasn't her job, at the very least she needed to report that the various advances in favour of Watson to those whose job it is, the Court of Appeal. As witnesses crucial to Watson's identification and proximity to the deceased at particular times were no longer resolute on their previous evidence in became a matter for the proper consideration by The Court of Appeal. Rather than noting Diplock's assertion that mercy 'begins where legal rights end' she dismembered the petition denying Watson the test of evidence which goes the 'safeness' of his conviction, singularly and in totality. This despite the manner spelt out in both the Bain and Lundy PC Judgements as to how such evidence should be treated. McDonald effectively set herself up as a Judge, who had a 'right' to use selectively, or omit, legal precedent - in each instance that was to the detriment of Watson and to the 'benefit' of a Crown case that if not in tatters has lost crucial pieces of it's narrative. McDonald papered over the cracks of a 'story' gone wrong and one which now there is considerable doubt a Jury would convict upon.
# In essence the 2 failures above (which are more expansive than is traversed here,) where 'nestled behind' a 'catchall.' Two hairs on a blanket. The public got to hear the Minister of Justice Judith Collins say that the 'two hairs' sustained the conviction. In other words, witnesses who now say they wouldn't, or couldn't now identify Watson as a person alleged to have been identified in company with the deceased, a critical witness who had recanted having heard a confession, extreme doubt about the vessel the couple boarded in the company of a man (no longer clearly Watson in the now fractured dialogue) were swept aside on the basis of 2 hairs. As to those 2 hairs, and anticipating that a new Jury would hear the amended evidence of eye witnesses who could now not put Watson with the couple where formerly they could, the abandonment of The Crown case by one of it's most important witnesses, a more specific examination of sailing times that do not 'assist' the Crown version they can not, and are not, 'a catchall.' There is no evidence that they were, as is alleged, from Olivia Hope, but were rather from a broad genetic pool that may have included Olivia. Not only that they 'had a history' of appearing 'when they were needed,' the two hairs were 'not found' on a earlier search, they were found after the 'delivery' of bag containing hair samples taken from the Hope home in a bag which it appears had a split on one side.
The evidence of the hairs needs support of other evidence, ie positive identifications, the 'right' (in fact sadly the wrong) people boarding the 'right' vessels in the harbour that morning. Also, of course a 'genuine' witness attesting to a 'confession.' All of these things would make up the short fall in the credibility of the case against Watson that the Minister and McDonald have said can rely on 2 hairs from an unconfirmed source. Instead we see the 'fallen short' evidence supported by other evidence similarly short of the mark. How it goes in a 'real' Court is that Judges look at the weakened points, new evidence and indeed any evidence which goes to the centre of a conviction which is then individually assessed, then collectively assessed firstly to the mind of Judges, duty bound to consider the 'safety' of a conviction, then also by the same Judges as to how a Jury might consider the points individually and in totality with the caution that they are not the Jury and can not undertake the function of a Jury.
Watson has been hung out to dry. If McDonald, indeed the Minister now needs to rely parts of a case to hold together others which are fractured, that plank, or construction steel cannot itself be of suspect condition. It must be of absolute certainty, even then, with so many 'grey' areas now evident in the Crown case it is for a Court of Law to rule, not a defacto Judge working at the behest of a Minister on a narrow scope that is contradictory to the Law, precedent and practice as to how the concept of 'Mercy' is available to citizens for whom all other avenues toward their freedom are closed. I anticipate the Scot Watson may now be waiting for the Judicial Review process in Bain to be completed so as to learn what the Court's view is in contemporary time as to the rights of us all to know there is something to be found 'where legal rights end,' that is not merely paper to cover over the cracks of injustice.