Here is what I wrote about Smith v Maryland and the third party doctrine two years ago.
The US government’s justification for the collection and use of telephone metadata pertaining to US citizens by the National Security Agency (NSA) exposed by Snowden was based on the third-party doctrine, derived from the above judgments (Savage, 2013). A 2013 decision from the District Court of the District of Columbia (perhaps the most important, because Washington DC is within the District) attracted significant attention because it explicitly contradicted the Smith rationale, stating that the surveillance of meta-data in 2013 was qualitatively different from that which was decided in 1979. However, a subsequent decision by a District Judge from the Foreign Intelligence Surveillance Act (FISA) Court responsible for oversight of the National Security Agency’s surveillance activities reaffirmed the third-party doctrine. Until the various appeals work their way up to the Supreme Court, Smith v Maryland will continue as the ruling precedent in the US. As stated by the FISA judge: “The Supreme Court may someday revisit the third-party disclosure principle in the context of 21st-century communications technology, but that day has not arrived” (Savage, 2013).”
It must be noted that there is no question in either Miller or in Smith about whether the bank and the telephone company could use the data. The only question at issue was whether the data could be given to a third party, the government, without the data subject’s authorization. Since the focus here is on use of transaction-generated data by third parties, the privacy problem or harm may be restated as one of harms cause by aggregation and identification at the individual or collective levels, as discussed above.
As predicted, the US Supreme Court has ended the third party doctrine, as reported in NYT:
In a pair of recent decisions, the Supreme Court expressed discomfort with allowing unlimited government access to digital data. It limited the ability of the police to use GPS devices to track suspects’ movements, and it required a warrant to search cellphones.
Technology companies including Apple, Facebook and Google filed a brief urging the Supreme Court to continue to bring Fourth Amendment law into the modern era. “No constitutional doctrine should presume,” the brief said, “that consumers assume the risk of warrantless government surveillance simply by using technologies that are beneficial and increasingly integrated into modern life.”
Older Supreme Court decisions offered little protection for information about businesses’ customers. In 1979, for instance, in Smith v. Maryland, the Supreme Court ruled that a robbery suspect had no reasonable expectation that his right to privacy extended to the numbers dialed from his landline phone. The court reasoned that the suspect had voluntarily turned over that information to a third party: the phone company.