What can happen if you don’t authenticate text messages and then use them as crucial evidence in your case? A total disaster!
A prosecutor in Pennsylvania learned this lesson the hard way, having a drug conviction overturned because of hearsay text messages. As with all evidence, the key is authentication.
Here’s the basic rule: Before you can introduce a writing into evidence, you have to make a preliminary showing of relevance to the issues to be decided in the action. This usually entails authenticating the writing, i.e., proving that it was made or signed by its purported maker. Evid C §1401(a); Comment to Evid C §1400.
Regardless of whether the evidence is a traditional form of writing or an electronic record, you must either introduce evidence sufficient to sustain a finding that it is the writing that the proponent of the evidence claims it is, or establish those facts by any other means provided by law. Evid C §1400.
The need to authenticate evidence was clearly lost on the Pennsylvanian prosecutor. As reported in the ABA Journal, the Pennsylvania appeals court overturned the drug conviction because the text messages on the defendant’s phone that were admitted as evidence at trial were not authenticated.
Not sure how to authenticate a text message? Don’t be thrown by the new technology, it’s the same as with other writings.
Text messages can be authenticated under California law through:
- Direct testimony of a witness who saw the messages created or executed (Evid C §1413);
- Distinctive characteristics of the message itself (Evid C §1421); and
- Circumstantial proof of authenticity (see Evid C §1410).
And don’t forget about “reply authentication,” by which you can authenticate a text message received in response to an initial sent message through the initial message. Evid C §1420.
Federal law similarly requires authentication of text messages. The Bow Tie Law blog shares an illustrative case that includes a “thoughtful opinion on the rules of Evidence and authenticating text messages.”
For everything you need to know about authenticating writings and the admissibility of electronic evidence, turn to CEB’s Jefferson’s California Evidence Benchbook, chaps 31 and 33 and Effective Introduction of Evidence in California, chap 11. Also check out CEB’s program How to Correctly Introduce Evidence at Trial, available On Demand.
Related CEB blog posts:
- 10 Questions to Ask Yourself Before Presenting Evidence at Trial
- Exclude Evidence Early: Using an In Limine Motion
- Facebook Postings as Evidence: They Are Not Just for Social Networking Anymore
© The Regents of the University of California, 2011. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited.
Filed under: Civil Litigation, Criminal Law, Evidence, Legal Topics Tagged: | admissibility, authentication, evidence, hearsay, introducing evidence, text messages, trial


Nice article, thank you.
Very helpful…thank you!