Today, the Supreme Court of Canada (SCC) answered an important question: when police execute a warrant to search a building, and they find computers or cell phones in that building, can they search the data stored on the computers even if the warrant doesn't explicitly authorize such a search? And their answer was: No.
That's simplifying things. A lot. For a slightly less simplified version, read on.
In R. v. Vu, the accused was suspected of running a grow op. The police obtained a warrant to search his home for evidence of "theft of electricity". The warrant did not explicitly authorize the search of any computers that might be found, though it did authorize a search for "computer generated documents". At the time of the search, existing law held that "[a] warrant authorizing a search of a specific location for specific things confers on those executing that warrant the authority to conduct a reasonable examination of anything at that location within which the specified things might be found”. One concrete example of this general proposition is that when police search a home, they are entitled to search receptacles within the home: cupboards, closets, boxes etc.
When the police searched the accused's home, they found marijuana growing in the basement. They also found two computers and a cell phone in the living room. The police searched both computers and the phone. At trial, the accused claimed that the search of the computers and the phone was a violation of his right to be secure against unreasonable search and seizure under section 8 of the Charter of Rights and Freedoms. The case wound it's way through the court system and eventually ended up at the SCC, who were faced with the following question: are computers and cell phones receptacles that can be searched without explicit authorization or should they be treated differently?
(From here on out, I'm just going to talk about "computers" rather than saying "computers and cell phones" every time. Unlike the Alberta Court of Appeal, I do consider most cell phones to be computers and it's clear from this judgment that the SCC agrees. I don't see any reason to keep making a distinction).
The SCC found that computers are not just receptacles, for a number of reasons. First, vastly more information can be stored on a computer than a typical receptacle. Unlike a cupboard, a computer “can be a repository for an almost unlimited universe of information”. Second, computers can store information that was automatically generated, sometimes in a manner completely unknown to the user. This can include browser history and old versions of word processing files. Third, computers can retain information even when a user thinks they have destroyed it. Fourth, computers connected to the Internet can give investigators access to far more information than just the information stored on that particular computer. All of these factors taken together mean that a search of a computer gives an investigator a far more intimate look into the private life of the accused than they would get from searching a cupboard. This justifies treating searches of computers differently.
From the case summary:
In effect, the privacy interests at stake when computers are searched require that those devices be treated, to a certain extent, as a separate place. Prior authorization of searches is a cornerstone of our search and seizure law. The purpose of the prior authorization process is to balance the privacy interest of the individual against the interest of the state in investigating criminal activity before the state intrusion occurs. Only a specific, prior authorization to search a computer found in the place of search ensures that the authorizing justice has considered the full range of the distinctive privacy concerns raised by computer searches and, having done so, has decided that this threshold has been reached in the circumstances of a particular proposed search. This means that if police intend to search any computers found within a place they want to search, they must first satisfy the authorizing justice that they have reasonable grounds to believe that any computers they discover will contain the things they are looking for. If police come across a computer in the course of a search and their warrant does not provide specific authorization to search computers, they may seize the computer, and do what is necessary to ensure the integrity of the data. If they wish to search the data, however, they must obtain a separate warrant.
So there we have it. A statement from the top court in the country that when police find computers while executing a warrant, they have to get a separate warrant to search those computers. Of course, it's also useful to look at what the SCC did NOT say. This decision does NOT mean that police can never search a computer:
 It is not my intention to create a regime that applies to all computers or cellular telephones that police come across in their investigations, regardless of context. As the respondent correctly points out, police may discover computers in a range of situations and it will not always be appropriate to require specific, prior judicial authorization before they can search those devices. For example, I do not, by way of these reasons, intend to disturb the law that applies when a computer or cellular phone is searched incident to arrest or where exigent circumstances justify a warrantless search. Rather, these reasons relate to those situations where a warrant is issued for the search of a place and police want to search a computer within that place that they reasonably believe will contain the things for which the search was authorized.
The SCC also did not go as far as requiring that when a warrant is issued for the search of a computer, that warrant must be constrained by "search protocols" which dictate how the computer may be searched:
 The intervener the British Columbia Civil Liberties Association submits that, in addition to a requirement that searches of computers be specifically authorized by a warrant, this Court should also find that these warrants must, as a rule, set out detailed conditions, sometimes called “ex ante conditions” or “search protocols”, under which the search may be carried out. According to the B.C.C.L.A., search protocols are necessary because they allow authorizing justices to limit the way in which police carry out their searches, protecting certain areas of a computer from the eyes of the investigators. The Crown and intervening Attorneys General oppose this sort of requirement, arguing that it is contrary to principle and impractical. While I am not convinced that these sorts of special directions should be rejected as a matter of principle, my view is that they are not, as a general rule, constitutionally required and that they would not have been required in this case.
I'm happy to see this decision. We don't need another repeat of that ridiculous Alberta Court of Appeal decision.
(Hat tip to David Fraser for this one).