Earlier this month the Ninth Circuit Court of Appeals became the third federal appellate court this year to hear argument on the legality of the NSA’s bulk collection of telephone metadata.

The legal battle over the constitutionality of warrantless government surveillance of cellular data networks reached the Ninth Circuit in Smith v. Obama. A Verizon Wireless customer filed suit to enjoin the government from collecting or using cellular network data gathered through the National Security Agency’s (“NSA”) bulk telephone metadata collection program. The District Court for the Northern District of Idaho denied the injunction in June of this year, citing controlling precedent that denies Fourth Amendment protection to information that users voluntarily disclosed to third party telecommunications companies.

This is the third such case to reach a federal appellate panel since Edward Snowden revealed last year that the NSA has been mining Americans’ telephone records without probable cause under Section 215 of the USA PATRIOT Act. Given the ubiquity of Americans’ cellular data network use – and already divergent opinions from the district courts – a fresh interpretation of the Fourth Amendment for the 21st Century may be on the horizon.

The central issue in these NSA telephone metadata collection cases is whether the Supreme Court’s so-called “third party doctrine” remains applicable in cases invoking the Fourth Amendment’s guarantee against unreasonable searches in an era when telecommunications companies hold so much of our personal information. The doctrine, as first explained in 1979 in Smith v. Maryland, provides that there can be no reasonable expectation of privacy in information that a citizen turns over to a third party. For example, a person who dials a telephone number forfeits any privacy right in the number dialed (but not the content of the conversation) because she communicated it to her telephone provider—a third party. Thus, according to advocates for the United States, the Fourth Amendment has no application to the NSA’s collection of telephone metadata (which does not include call content) because each user voluntarily provided the information to a telecommunications company.

This argument for extending the third party doctrine unchanged into the realm of NSA data mining has met with mixed reactions over the past year. In Klayman v. Obama (D.D.C. Dec. 16, 2013) Judge Richard Leon held the NSA likely violated the Fourth Amendment by mining cellular data without a warrant, reasoning that the rise of cell phone use and the mosaic of personal information held by telecommunications companies rendered Smith v. Maryland too outdated to control a case in the digital age.

Mere weeks later, however, Judge William H. Pauley held the exact opposite in ACLU v. Clapper (S.D.N.Y. Dec. 27, 2013) noting that Smith v. Maryland was still good law notwithstanding the changed circumstances inherent in the scope of data that now falls within the third party doctrine. The Second Circuit heard oral argument in Clapper on September 2, 2014, and the D.C. Circuit heard arguments in Klayman on November 4, 2014. Orders have not yet been released in either case.

Smith v. Obama does not present new and distinct legal issues from the prior NSA surveillance cases, but derives its importance from its timing. Judge Winmill’s opinion for the District Court for the District of Idaho did little more than note Smith v. Maryland was the controlling precedent and urge the Ninth Circuit on appeal to keep the issue alive for final resolution by the Supreme Court. In particular, he indicated the Justice Sotomayor would likely be willing to reconsider Smith v. Maryland given the opportunity, and that the Klayman opinion “should serve as a template for a Supreme Court opinion.” Such an assertion by a trial judge seems presumptuous at first glance, but with the legality of NSA surveillance now pending before three federal appellate courts, final resolution by the high court is growing more likely. A circuit split on a national security issue of this caliber is not likely sustainable from any party’s point of view.

It’s likely that all three federal appellate courts addressing the issue will render decisions in 2015, so stay tuned for further developments in this area.