What is the test for “plain view” searches in the context of the search warrant?

His Lordship concluded: “Without being exhaustive of all situations, I draw the following legal principles from the foregoing: (i) when police officers lawfully enter a premises under the authority of a search warrant obtained validly and in good faith, they are entitled to search for those items listed in the warrant; (ii) they must act only within the scope and ambit of the warrant having regard to the description of the premises and the owner or occupant of the premises and the range and type of items set out in the warrant; (iii) if in doing so, they see an item or items in plain view which they believe on reasonable grounds is evidence of a criminal offence, they may record all relevant observations of such items for use in applying for a search warrant for such items; (iv) the requirement of ‘reasonable grounds’ will be tested and satisfied by the review of the application for the subsequent warrant by the justice before any further violation of anyone’s privacy interest is allowed, not after, in keeping the principles in Hunter v. Southam Inc., supra; and (v) S. 489 should be resorted to as authority for seizure of items beyond the scope of the search warrant only where exigent circumstances regarding preservation of evidence exist making it not possible to obtain a further search warrant. In my view, s. 8 of the Charter and the decision in Hunter v. Southam and subsequent cases following it indicate the importance of the privacy interest protected by s. 8 of the Charter and shared by all citizens and residents of this country. It protects against unreasonable searches and seizures, and those searches and seizures carried out without prior authorization or beyond the scope of any prior lawful authorization are presumed to be unreasonable unless the contrary is shown. I think it is far better to rely on objectively determinable standards for the substantial purposes of s. 8 of the Canadian Charter, rather than on the subjective standards attempted to be reconstructed objectively after the event required by the American 4th Amendment cases. No doubt a further and better enunciation of the kind of objectively determinable standards of search and plain view will be forthcoming as the experience of the law unfolds. For now, I feel it is dangerous to take s. 489 too far in allowing unfettered ‘plain view’ seizures where the Charter requires a reasoned but real protection for individual privacy, and from intrusions on that privacy unnecessarily by the powers of the state. That section, so far as I am aware, has not been tested directly against Charter principles.”