The Shawcross doctrine is not a legal rule. It was expounded in parliamentary debates in 1951. We have no caselaw, no strict interpretation.
The doctrine comes down to the fact that decisions are made by the Attorney General. So any discussion of information would be problematic if instructions were given, if pressure was exercised, or if there was any interference in a decision.
Normally, to my knowledge, any advice must be sought. Currently, however, I believe that no one can categorically and definitively state that the theory absolutely excludes the Attorney General being given information that has not been sought. Mr. Forsece, a colleague of mine from the University of Ottawa, suggested as much in a post.
What I am saying is that there is enormous speculation over a convention that basically comes from a parliamentary debate. There are learned theoretical debates, but no one can make the assumption that we are dealing with a rule that is extremely clear.
The essence of the convention is that discussions must not have prevented the AG from making the decisions himself, and that the AG is responsible for not allowing himself to be influenced. If that is the case, he should resign.