I suggested that Sinclair will have to be applied in a way that preserves the defendant's absolute right to a fair hearing. This too is a requirement of Cadder. All members of the Court agreed with the two leading judgments (although technically Lord Mance agreed with Lord Hope but through him also agreed with Lord Rodger). Lord Rodger put the relationship between the non-absolute right to legal assistance and the absolute right to a fair trial this way (95):
"First, as the European Court recognises, [in Salduz v Turkey] 49 EHRR 421, 437, para 55, since the right to legal assistance at the stage when a suspect is to be questioned is an implied right, it is not absolute and must be subject to exceptions when, in the particular circumstances, there are compelling reasons to restrict it. It is not suggested that there would have been any such reasons in this case. But the circumstances in which section 15 of the 1995 Act envisages delaying intimation to a solicitor (the interest of the investigation or the prevention of crime or the apprehension of offenders) could perhaps constitute compelling reasons to restrict the right of access in an appropriate case. It has to be remembered, however, that even a justified restriction may deprive an accused of a fair hearing and so lead to a violation of article 6: 49 EHRR 421, 436, para 52."
Key concepts are the "compelling reasons" needed before the right to legal assistance can be restricted, and the nature of the "fair hearing". Neither of those called for detailed consideration in Cadder.
I doubt that in practice the correct application of Sinclair will produce different outcomes in Canadian courts from those in Scottish courts under Cadder.
Lord Rodger at 100-103 also dealt with the argument that changing the law of Scotland now would create a need to revise all the decisions that had applied the earlier law, by applying dicta in A v The Governor of Arbour Hill Prison  4 IR 88, per Murray CJ at paras 36-38.
Lord Hope referred to Gafgen v Germany (a case discussed here on 3 July 2008, 3 December 2008, and 25 June 2010, and also in Part 3 of the overview of these notes posted on 14 January 2010). He held at 48 that Gafgen turned on it's facts and was not a limitation of Salduz.
With there now being less wriggle-room concerning rights compliance, attention will focus on whether waiver of the right to legal advice had been constituted by the defendant's continuing cooperation with police questioning.