Supreme Judicial Court of Massachusetts Questions Whether Lay Witness Can Testify About Metadata, Cache, and Cookies

January 24, 2025

Federal Rule of Evidence 701 provides that

If a witness is not testifying as an expert, testimony in the form of an opinion is limited to one that is:

(a) rationally based on the witness’s perception;

(b) helpful to clearly understanding the witness’s testimony or to determining a fact in issue; and

Massachusetts doesn’t have official rules of evidence, but it has an Evidence Guide, with Section 701 of its Guide mirroring its federal counterpart. So, in 2025, are lay witnesses able to testify about concepts such as cookies, metadata, and cache, or does that still require expert testimony? That was the question addressed by the Supreme Judicial Court of Massachusetts in its recent opinion in Commonwealth v. Cronin, 248 N.E.3d 142 (Mass. 2025).

Cronin was a child pornography case, with Police Officer Michael McLaughlin testifying as a lay witness about the system used to extract data from defendant’s cell phone. The Supreme Judicial Court of Massachusetts mostly found that Officer McLaughlin’s testimony was proper lay witness testimony, albeit with him (harmlessly) crossing the line by testifying about the system’s safeguards against data alteration (which required expert testimony).

In addition, the court noted that following:

Finally, McLaughlin’s explanation of technical concepts — such as cookies, metadata, and cache — poses a closer call. On the one hand, “[c]ourts routinely conclude that the interpretation and analysis of metadata requires an expert qualified in the field.” Allegis Group, Inc. v. Bero, 689 F. Supp. 3d 81, 108 (D. Md. 2023) (collecting cases). On the other hand, computers, cell phones, and other electronic devices are ubiquitous….Given this technological ubiquity, basic technical terms and concepts may be within the common understanding of lay people. See Mason, 485 Mass. at 538, 151 N.E.3d 385 (witness’s testimony concerning her Internet search constituted lay opinion). See also State v. Webb, 2023-Ohio-4050, ¶ 37, 228 N.E.3d 61 (Ct. App.) (“The trial court did not abuse its discretion when it allowed the state to introduce the metadata without expert testimony…[given that a] layperson could understand, without expert help, that the information which appeared includes the date, time, and order in which the photos were taken”). Nevertheless, even assuming that the admission of this testimony was erroneous, as explained below, any error was nonprejudicial.

All of which prompts the question: In 2025: Are the concepts surrounding cookies, metadata, and cache ubiquitous enough in 2025 that they allow for lay witness testimony, or should we still require experts to explain these concepts?

-CM