Confessions and a "person in authority"

R. v. S.G.T., 2010 SCC 20, released this morning, deals with the confession rule in the context of a statement made to someone who is not, at least on the surface, a "person in authority". The entire decision is worth close reading. This note deals with just one aspect of the case.  

When statements are made by an accused to ordinary persons, they are presumptively admissible, as admissions by an opposing party, without the necessity of a voir dire.  It is only where the accused makes a statement to a "person in authority" that the Crown bears the onus of proving the voluntariness of the statement as a prerequisite to its admission, under the confessions rule.  To be considered a person in authority, the accused must believe that the recipient of the statement can control or influence the proceedings against him or her, and that belief must be reasonable. 

The accused must provide an evidential basis for claiming that the receiver of a statement is a person in authority.