The Massachusetts Supreme Judicial Court has issued a new decision interpreting the Massachusetts constitution to require a search warrant for access to a two-week span of historical cell-site information. The court divided by a vote of 5-2. Note that the decision did not interpret the Fourth Amendment of the federal constitution, but rather interpreted Article 14 of the Massachusetts Declaration of Rights. This means that the decision is binding on Massachusetts state law enforcement, but it does not apply to federal law enforcement (whether in Massachusetts or outside it).

The decision appears to adopt a mosaic theory for the state constitution, by which the time of surveillance determines what is a state-constitution search. In this case, the government obtained a court order requiring the cell-phone provider to hand over historical cell-site records covering a two week period. The Massachusetts court concludes that if the court order had covered a short time, it would not have triggered the state constitution. But by ordering the disclosure of records covering a two week period, that was long enough to trigger a warrant requirement under the state constitution:

[T]here is some period of time for which the Commonwealth may obtain a person’s historical CSLI by meeting the standard for a § 2703(d) order alone, because the duration is too brief to implicate the person’s reasonable privacy interest. But there is no need to consider at this juncture what the boundaries of such a time period might be in this case because, for all the reasons previously rehearsed concerning the extent and character of cellular telephone use, the two weeks covered by the § 2703(d) order at issue exceeds it: even though restricted to telephone calls sent and received (answered or unanswered), the tracking of the defendant’s movements in the urban Boston area for two weeks was more than sufficient to intrude upon the defendant’s expectation of privacy safeguarded by art. 14.

As I wrote in my mosaic theory article, it will be interesting to see how courts turn this into rules. For example, if one week is short-term enough not to get a warrant, what happens when the investigators get two one-week court orders individually instead of one two-week order? But then this is only a decision that regulates one state, and doesn’t apply at the federal level, so perhaps the issue won’t come up often enough to open the Pandora’s Box that I think the mosaic theory implicates.

Thanks to How Appealing for the link.