On April 16, 2026, a unanimous New Jersey Supreme court decided the Cumberland County case of State v. Jule Hannah. The principal issue under Evidence Rule 701 concerned whether a lay witness can testify regarding cell site location information (CSLI) — specifically, the locations of cell towers that cell phones connect to — or whether an expert witness is required.
Justice Pierre-Louis, my Rutgers Law classmate, wrote for the Court in relevant part: Defendant Jule Hannah was charged with the murder of Miguez Lopez. Detective Sergeant Kenneth Leyman obtained defendant’s cell phone records. The State asserted at trial that these records supported its theory that Lopez picked defendant up in Monroe Township and that the two men then crashed nearly an hour later in Bridgeton, where Lopez was found shot to death. In addition to the phone records, the State introduced the testimony of a forensic scientist that a cigar butt found in Lopez’s car matched defendant’s DNA, as well as evidence of a recorded phone call in which a third person can be heard in addition to Lopez and the caller. Prior to defendant’s trial, the trial court allowed Detective Leyman to testify as a lay witness regarding his use of phone records to map the locations of cell towers that relevant cell phones, including defendant’s, connected to during the pertinent time period surrounding Lopez’s death. In limiting the scope of Detective Leyman’s testimony as a lay witness, the trial court stressed that there was to be no testimony “about the location of any phone at any particular time.” The trial court also gave several limiting instructions to the jury during Detective Leyman’s testimony, directing that they should not consider CSLI alone as evidence that a phone was in a particular place and advising that a cell phone’s connection to a cell tower does not indicate whether the cell phone was in any particular location.
Despite the trial court’s instructions, Detective Leyman testified that the CSLI could indicate where a suspect was at the time of Lopez’s death. His testimony also associated the cell towers to which defendant’s cell phone connected to the path Lopez traveled that day, consistent with the State’s theory that defendant was in Lopez’s car prior to the homicide. Then, in summation, the State told the jury that a cell phone must be close to the tower it connects to, stating that its proximity must be “a stone’s throw” away. The jury convicted defendant of first-degree murder and unlawful possession of a weapon. The Appellate Division reversed defendant’s conviction, finding the trial court erred in allowing Detective Leyman to testify about historical CSLI without being qualified as an expert. The Appellate Division further concluded that this inference carried significant weight in a case built largely on circumstantial evidence, where the only physical link between defendant and the victim’s vehicle was DNA on a cigar butt. The Appellate Division found the trial court’s limiting instructions insufficient to cure the prejudice caused by Detective Leyman’s testimony.
County Prosecutor offices are well-funded. The State has an enormous resource advantage over the average person. In a murder case, the State had good reason and the ability to hire an expert witness regarding cell site location information. A fair inference is that no reputable expert would have testified to the detective’s inculpatory claims.
Justice Pierre-Louis continued in relevant part: Pursuant to N.J.R.E. 702, CSLI involves technical and specialized knowledge that must be presented to a jury by an expert witness at trial. N.J.R.E. 701 provides the applicable standard for courts to determine the admissibility of lay witness testimony. A lay witness may give an opinion on matters of common knowledge and observation. When testimony requires an opinion on a matter beyond common knowledge and observation, however, Rule 702 provides for the admission of expert testimony and discusses circumstances in which an expert may testify. In case law, courts have identified circumstances in which an expert — as opposed to a lay witness — must testify; that is, topics that can be raised only if an expert will testify. In broad terms, when a subject is so esoteric that jurors of common judgment and experience cannot form a valid conclusion, expert testimony is required. A jury should not be allowed to speculate without the aid of expert testimony in any area where laypersons could not be expected to have sufficient knowledge or experience.
Although expert witnesses may testify to subjects that lay witnesses may not, their testimony must remain grounded in facts or data derived from (1) the expert’s personal observations, or (2) evidence admitted at the trial, or (3) data relied upon by the expert which is not necessarily admissible in evidence but which is the type of data normally relied upon by experts. An expert’s bare opinion that has no support in factual evidence or similar data is a mere net opinion which is not admissible and may not be considered.
The Court reviews how cellular networks operate, the relationship between cell phones and cell towers, and the import of CSLI. The user’s proximity to a cell site is significant in determining which tower has the strongest signal. However, the strength of the signal is also influenced by the technical characteristics of the towers; geography and topography; the angle and number of antennas; the features of the phone itself; and environmental and geographical factors. Generally, courts agree that an expert, not a lay witness, must present testimony regarding technical aspects of cell towers and CSLI. Many courts, however — including some that have required expert testimony as to the technical aspects of CSLI — have concluded that a witness may provide limited testimony about the contents of call records detailing the locations of cell towers utilized by a phone without being qualified as an expert.
But Maryland courts have rejected the argument that a layperson with the same phone records and instructions could have determined the location of the cell sites from such records. Although the Court has not previously considered whether CSLI testimony must be offered by an expert, it recently held that expert CSLI testimony that a defendant’s cell phone was likely near a crime scene was an inadmissible net opinion because it lacked factual evidence or objective data. See State v. Burney, 255 N.J. 1 (2023). In Burney, the expert’s estimate of a cell tower coverage radius was based solely on the agent’s personal “rule of thumb,” without reference to supporting data, scientific calculations, or specific tower characteristics such as height, power, or surrounding terrain.
Here, the trial court’s repeated attempts to instruct the jury regarding CSLI — see pages 10 to 23 of the Court’s opinion — illustrate the complexity of that testimony and demonstrate exactly why such evidence must be presented by an expert witness. A jury, properly informed about the intricacies and nuances of cell towers, should be able to use CSLI to place a phone in a general area. But that cannot happen if a jury is not properly equipped with the tools necessary to understand this relevant evidence. Further, leaving the jury to draw any inferences it deemed appropriate from the non-contextualized CSLI evidence — without a full explanation of its technical aspects and capabilities by an expert witness — also risked confusing and misleading the jury in violation of N.J.R.E. 403. Although a jury may be able to figure out the location of cell towers using phone records, it would not be able to draw any meaningful inferences from that information without an understanding of how cell towers operate and why those cell tower locations matter. And, in the absence of expert guidance, a jury could attribute more or less weight to the tower locations than is warranted.
The Court disagrees with the approach taken by many jurisdictions — allowing witnesses to provide limited testimony about the locations of cell phone towers that cell phones connect to without being qualified as an expert. The technical and specialized knowledge required to interpret CSLI is beyond the ken of the average juror. Finally, the CSLI testimony that the jury heard in this case, is at odds with Burney. If an expert attempted to offer the same conclusory information that Detective Leyman did, that expert’s testimony would constitute an impermissible net opinion in violation of N.J.R.E. 703 because the conclusions were unsupported by adequate data. The State cannot circumvent the standards to which expert testimony is held under N.J.R.E. 702 by presenting the testimony through a lay witness rather than an expert.
