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The Carpenter Case and Other Privacy-Related News

By John DiGiacomo

As we discussed in the last few weeks, privacy is repeatedly in the news. Washington lawmakers are trying again to update the Electronic Communications Privacy Act, the Stored Communications Act (the “SCA”), and the Pen Registry Act.

In addition, last month the US Supreme Court granted certiorari in the case of Carpenter v. United States. While ostensibly a Fourth Amendment privacy case, we here at Revision Legal know that privacy frameworks established by the courts under the Fourth Amendment have migrated into statutory law.

Good examples, and also relevant to understanding Carpenter, are privacy laws related to wiretaps and pen registers. In the case of Katz v. United States, 389 U.S. 347 (1967), the US Supreme Court held that citizens had a “reasonable expectation of privacy” in their phone calls and would not expect them to be intercepted or recorded. Thereafter, law enforcement officials were required to obtain warrants for wiretaps. This legal framework was subsequently incorporated by Congress into the 1968 Wiretap Act.

A physical wiretap is not the only method of obtaining information about your phone calls. With various devices generally known as pen registers or trace and trap devices, information can be gathered about what phone numbers you have called and what phone numbers have called you.

In Smith v. Maryland, 442 U.S. 735 (1979), the Supreme Court held that no warrant was needed to obtain that type the information. According to the Court in Smith, there was no expectation of privacy in this information because you know the phone company knows the number you are dialing — in fact, it needs the number you are dialing to make the connection. You have disclosed it voluntarily to a “third party.” Because of this and because the pen register does not intercept your actual conversation, the Supreme Court ruled that use of a pen register or similar device does not constitute a “search” for purposes of the Fourth Amendment. In other words, no warrant is needed.

The permissive rule of Smith v. Maryland was then subsequently adopted by Congress in the Stored Communications Act (“SCA”) and the Pen Register Act (“PRA”), both enacted in 1986 as subsections of the Electronic Communications Privacy Act. This legislation applied various laws concerning telephones and beepers to other electronic communications. Congress incorporated the lenient Smith standard into these new laws. The SCA and PRA allow law enforcement to set up a pen register or obtain certain information about stored electronic communications with an ex parte court order if it is certified that the expected information is “relevant to an ongoing criminal investigation.” See 18 U.S.C. § 3123(a)(1).  That is a much easier standard to meet than the probable cause standard needed for a warrant.

In general, Fourth Amendment privacy cases can be highly predictive of future actions by Congress.

Carpenter v. United States.

Carpenter v. United States raises privacy issues related to what has become known as cell site location information (“CSLI”). Under the SCA and PRA, CSLI information is treated in the same manner as information gathered by a pen register. That is, law enforcement can obtain CSLI information with the basic court order described above. No probable cause need be shown, no warrant is needed.

According to the Pew Research Center, over 95% of Americans own a cellphone and the share of smartphones is now 77%, up from 35% in 2011.

All cellphones collect and store CSLI information. Each cell tower in a service area contains devices that receive and transmit electronic signals. Your cellphone also receives and transmits signals. Your phone “pings” the nearest cell tower, and this enables you to get service. This back-and-forth signaling occurs when you make or receive a call or a text or if some app on your phone signals for an update. If you have a smart phone, your phone is constantly sending and receiving electronic signals as you are connected to the internet. These transmissions are stored and can be used to establish your general geolocation. Given overlapping transmission radii, triangulation can pinpoint your geolocation quite precisely.

This CSLI data is stored by your service providers and the police can obtain a court order to obtain the data from many service providers.

This is the issue raised by Carpenter v. United States. In Carpenter, the defendant was charged with various armed robberies over several weeks. The prosecutors were allowed to introduce 127 days worth of CSLI data showing that the defendant was in the geospatial area of the robberies at the various times that the robberies were committed. The CSLI data had been obtained without a warrant. The trial judge admitted the CSLI evidence over objection and the defendant was convicted. On appeal, the Sixth Circuit affirmed. See Carpenter v. United States, 819 F. 3d 880 (6th Cir. 2016).

The Sixth Circuit held that the CSLI data was similar to the pen register data collected in Smith v. Maryland. Everyone knows that, for their cellphones to work, their phones must connect to celltowers. Moreover, everyone has to set up their phones, enter various information, enable various programs, etc. As such, citizens do not have an expectation of privacy with respect to this information since, in the Sixth Circuit’s view, we all know this information is being shared with our service providers. Therefore, according to the Sixth Circuit, the rule of Smith applies.

The counter-argument is, of course, that information about us — pen register information — is qualitatively different than information disclosing where we are or where we were — CSLI data.


Carpenter is a difficult case to predict.

Two recent cases are particularly relevant. In Riley v. California, 134 S.Ct. 2473 (2014), the Supreme Court recognized privacy rights for what we store on our cellphone saying that, in many respects, a search of your cellphone is more intrusive and revealing than a search of your home. In United States v. Jones, 132 S.Ct. 935 (2012), the Court held it unconstitutional for law enforcement to physically place a GPS tracker on your car without a warrant. Some of the Justices were concerned about the physical “trespass” involved; other Justices were concerned about the length of time and the precision of the information gathered and expressed the view that there are significant expectations of privacy about where and when we drive. Both Riley and Jones were unanimous decisions.

One can discern several dichotomies being drawn and discussed in the various cases at the District, Circuit, and Supreme Court levels. Among these are:

  • Historical information vs. real-time
  • Generalized vs. precise information gathered
  • Small amounts vs. large amounts of data gathered
  • Non-content vs. content information
  • Other-gathered (e.g., phone company; service provider) vs. police-gathered

The courts seem to be less concerned about privacy issues with the first in each dyad above. For example, the Sixth Circuit in Carpenter distinguished Riley by noting that cellphones “store vast amounts of information about their users — vastly more, of course, than whether the user happens to be located within a two-mile radial wedge.”

How Carpenter is resolved may foretell future changes to privacy statutes such as the ECPA, the SCA, and the PRA. As we have said before, changes in the law require changes in how business operate.

Contact Revision Legal

We are prepared to help you understand new requirements and possibly new opportunities. We learn the changing law so you are free to run your business. You need the professionals at Revision Legal.

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