In a drug prosecution under Article 112a of the UCMJ, the government often wants to place the accused at a particular location: a stash house, a known dealer’s residence, a shipping point, or a spot inconsistent with the accused’s account. GPS tracking data, whether pulled from a phone, a vehicle device, or an installed tracker, is a powerful way to do that. But the data is not admissible simply because it exists. Trial counsel must lay an evidentiary foundation that satisfies authentication before a military judge will let the members consider it. This article explains what that foundation requires.
The Governing Standard: Military Rule of Evidence 901
Authentication of GPS data is governed by Military Rule of Evidence 901, which mirrors Federal Rule of Evidence 901. The rule sets a deliberately modest threshold. The proponent must produce evidence sufficient to support a finding that the item is what the proponent claims it is. This is a prima facie showing, not proof beyond a reasonable doubt and not even a preponderance determination by the judge. The judge decides only whether a reasonable member could find the data genuine; the ultimate weight is for the members.
Authentication is treated as a component of relevancy. If the data is not what the government says it is, it is not relevant, so the foundation question and the relevance question are intertwined. For GPS evidence, the proponent typically proceeds under two related provisions of Rule 901. One allows authentication through the distinctive characteristics of the item taken together with all the circumstances. The other, often the more important for machine-generated location records, allows authentication by evidence describing a process or system used to produce a result and showing that the process or system produces an accurate result.
Building the Foundation for the Device and the System
Because GPS data is generated by a system, the government must show that the system works and that it produced an accurate result. In practice that means establishing several things through testimony or documentation.
First, the source device must be identified and tied to the accused or to the relevant location. If the data comes from a smartphone, counsel must connect the phone to the accused. If it comes from a vehicle tracker, counsel must establish where and when the tracker was installed and on which vehicle. The link between the data and the person is what makes the location meaningful in an Article 112a case.
Second, counsel must describe how the system captures, calculates, and stores location. A witness familiar with the technology, whether a forensic examiner or a representative of the service or device, should explain that the system records position by reference to satellite signals, the general accuracy of those readings, and how timestamps are generated and stored. The point is to show the system reliably produces accurate location results.
Third, counsel must show the data was extracted and preserved without alteration. In digital forensics this is done by acquiring a forensic image and verifying it with hash values, a unique digital fingerprint of the data. If the hash of the working copy matches the hash of the original acquisition, the proponent can demonstrate the records were not changed after collection.
Chain of Custody and Metadata
Chain of custody supports, but is not strictly identical to, authentication. A documented chain shows who handled the device and the data, when, and what was done at each step, from seizure through extraction to courtroom presentation. Gaps in the chain do not automatically render evidence inadmissible, but they go to weight and can invite a defense challenge that the data was altered or confused with another source. A clean, dated, signed custody record makes the prima facie showing far easier.
Metadata embedded in the records, including timestamps and the coordinates themselves, is central to authenticity. Counsel should be prepared to explain the metadata and to show that it is internally consistent and consistent with other evidence in the case. Distinctive characteristics, such as a pattern of locations matching the accused’s known movements, can corroborate that the data is genuine.
Lawful Acquisition Is a Separate Question
Authentication answers whether the data is genuine. It does not answer whether the data was lawfully obtained. In an Article 112a prosecution, the defense may separately move to suppress GPS evidence on Fourth Amendment grounds if it was gathered without proper authorization, because tracking a person’s movements can constitute a search requiring a warrant or its military equivalent. Counsel should keep these issues distinct: a perfectly authenticated record can still be suppressed if the underlying collection violated the accused’s rights, and conversely, lawfully obtained data still needs an authentication foundation before the members may consider it.
Why This Matters in the Article 112a Context
Article 112a covers wrongful use, possession, manufacture, distribution, and related conduct involving controlled substances. GPS data rarely proves a drug element directly; instead it corroborates other evidence by placing the accused at a relevant time and place, undercutting an alibi, or linking the accused to a distribution network. Because the data is circumstantial, the foundation must be solid enough that the members can rely on the location with confidence. A weak foundation invites the judge to exclude the data or the members to discount it.
Summary
To authenticate GPS tracking data in an Article 112a case, the government must make a prima facie showing under Military Rule of Evidence 901 that the data is what it purports to be. That means identifying the source device and tying it to the accused, describing the system and showing it produces accurate location results, demonstrating through hashing and chain of custody that the data was preserved without alteration, and explaining the metadata. Authentication is a low but real bar, and it is separate from the lawful acquisition question that may be litigated through a suppression motion. Counsel who treat both questions seriously give the members reliable location evidence rather than a record vulnerable to exclusion.
Disclaimer
This article is provided strictly for general educational and informational purposes. It is intended to explain how the Uniform Code of Military Justice (UCMJ), the Rules for Courts-Martial, the Military Rules of Evidence, and related military administrative processes work as a matter of public legal education. It does not constitute legal advice, a legal opinion, or a recommendation about any particular case, and it is not a substitute for advice from a qualified military defense attorney who can evaluate the specific facts and command, service, and jurisdictional circumstances involved.
Reading this article, or contacting any website on which it appears, does not create an attorney-client relationship between the reader and any law firm, attorney, or author. Every court-martial, nonjudicial punishment action, administrative separation, and security-clearance matter turns on its own facts, the charged articles, the convening authority, the service branch, and the evidence, and outcomes vary widely from one case to another.
Military law also changes over time. The Military Justice Act of 2016 (effective January 1, 2019) and subsequent National Defense Authorization Acts renumbered and rewrote many punitive articles, revised the Article 32 preliminary hearing, and altered sentencing, clemency, and appellate procedures. Statutes, regulations, executive orders, the Manual for Courts-Martial, and decisions of the service Courts of Criminal Appeals and the Court of Appeals for the Armed Forces may have been amended, superseded, or reinterpreted after this article was written, and article numbers or procedures cited here may have changed.
For these reasons, no reader should act or decline to act based on this content without first consulting a licensed attorney experienced in military justice about their own situation. The author and publisher make no warranty, express or implied, as to the accuracy, completeness, timeliness, or current applicability of the information provided, and disclaim any liability for any action taken or not taken in reliance on it. If you are facing investigation, charges, or an adverse administrative action, time limits may apply, and you should seek qualified counsel promptly.