Cellular telephone billing records are another mundane aspect of modern life. They arrive monthly in the mail or online and hardly anyone I know (at least) spends any great amount of time reviewing them for accuracy or content. In most households, they go into the “to be paid” pile, where they reside until processing.

But telephones are no longer just telephones and cellular telephone bills, if parsed thoroughly and knowingly, can reveal on their face a startling amount of personal information and can provide entrée to much more. In 2016, cellular telephones must be viewed as small super computers and cellular telephone bills can yield as much information as banking or credit cards records can, if not more.

So, what should the government have to do in order to gain access to this potential treasure trove? This was the question addressed by the Supreme Court of New Jersey last month in State of New Jersey v. Lunsford.

Mr. Lunsford, it was alleged, was in the illegal drug business. As is often the last act in this type of drama, the police arrested him and executed a search warrant on his home. A short time later, a grand jury in Monmouth County issued a subpoena duces tecum to his wireless telephone service provider seeking information related to his cellular telephone. This information included customer billing records well as “call-detail records” which identify the numbers and timing of all incoming and outgoing calls.

Mr. Lunsford filed a motion to quash arguing that this information could not be subpoenaed, but need to be obtained only via a communications data warrant, the equivalent of a search warrant. This motion to quash was granted and after some procedural issues, the case ended up in the Supreme Court of New Jersey.

In an opinion written by Chief Justice Rabner, the Supreme Court agreed with the trial court, holding that due to many personal private affairs they provide access to, cellular billing records are worthy of constitutional level protection.

Thus, in order to gain access to these records, law enforcement must show relevance and this showing must receive the imprimatur of direct judicial oversight of the entire process. In short, a warrant is needed, not just a subpoena. And in obtaining such a warrant, the State is tasked with showing “specific and articulable” grounds to demonstrate that these records are relevant and material to an ongoing investigation.

A victory for privacy and process.