How to Authenticate Evidence in the Age of Deepfakes: A Checklist for Florida Litigators

Practical brief for Florida litigators, family lawyers and litigation paralegals.

Authentication used to be a formality for most photos, recordings and text messages. That is changing. Generative AI can now produce convincing fake video, audio, images and documents, and courts have started to see them. In Mendones v. Cushman & Wakefield, a California court issued terminating sanctions in September 2025 after finding that video exhibits filed with a summary judgment motion were deepfakes. ^[1]

The other side of the problem matters just as much. Once everyone knows fakes exist, authentic evidence gets attacked as “AI.” Researchers call this the “liar’s dividend.” ^[2] Either way, the side that can prove where its evidence came from has the advantage.

For the bigger picture on where this is heading, read our flagship piece, AI & PI: What Does the Future Hold? This article is the practical companion: a checklist you can use on your next case.

Start with the standard

In Florida, section 90.901 of the Evidence Code requires authentication as a condition of admissibility, and it is satisfied by “evidence sufficient to support a finding that the matter in question is what its proponent claims.” ^[3] Federal Rule of Evidence 901 uses the same basic test.

Federal rulemakers are studying whether that is enough. The federal Advisory Committee on Evidence Rules published a proposed Rule 707 on machine-generated evidence for public comment, then in 2026 sent it back for revision and further study together with the deepfake authentication question. ^[4] Until new rules arrive, the existing standard governs, and the burden falls on how well you build the foundation.

Checklist 1: Securing your own evidence

• Get the original file, not a copy. A screenshot, a forwarded video or a file re-saved by a messaging app has usually lost metadata. Ask the client for the original device or the original file.
• Preserve early. Send preservation letters for surveillance video, phone data, cloud accounts and social media before routine deletion or overwriting.
• Collect from the source. Public records should come from the clerk, the property appraiser or the state’s records, not from a third-party printout. Business video should come from the business that holds it.
• Document chain of custody from day one. Record who collected each item, when, from where, how it was stored and every time it changed hands.
• Keep the metadata intact. Collect native files and record identifying details at collection so you can later show nothing changed.
• Don’t enhance evidence with AI. “Cleaning up” a video or audio file with generative tools invites the challenge you are trying to avoid. If enhancement is needed, use a qualified forensic examiner who documents every step.
• Identify your foundation witness. Decide now who will testify to how each item was created and collected, and make sure that person can explain it under cross-examination.

Checklist 2: Testing the other side’s evidence

• Request native files and metadata in discovery, not PDFs or screenshots of messages and media.
• Ask who created it, on what device, and when. Depose the person who claims to have recorded it.
• Compare against known authentic material. In Mendones, the court compared the questioned videos with an authentic recording of the same witness and found clear differences in voice, cadence and expression. ^[1]
• Look for practical red flags: mouth movement that doesn’t match speech, looping or repeated motion, unnatural pauses, missing or inconsistent metadata, and a recording that surfaced late with no clear origin.
• Check the story around the file. Investigators can test whether the people, places and timeline in a recording match what can be documented independently.
• Bring in a forensic examiner when the stakes justify it. An investigator can develop the facts around a file. Technical analysis of the file itself is work for a qualified digital forensic expert.

Checklist 3: Florida limits on how evidence is gathered

Authentic evidence can still be excluded or create liability if it was gathered unlawfully.

• Recording: Florida generally requires every party’s consent to intercept a private conversation (§934.03), and unlawfully intercepted wire and oral communications cannot be received in evidence (§934.06). ^[5]
• Tracking: placing a tracking device or app on someone’s vehicle or device without consent is a crime under §934.425, with narrow exceptions. ^[6]
• Licensing: paid investigative work in Florida generally requires a Chapter 493 license. Verify any investigator on the FDACS website before the work starts. ^[7]

Checklist 4: Your own use of AI

• Follow Florida Bar Ethics Opinion 24-1. Protect client confidentiality, supervise the tools your team uses, and verify what they produce. ^[8]
• Remember Mata v. Avianca. Lawyers were sanctioned for filing AI-invented case citations. ^[9] Treat any AI output as a lead to check, not a fact.
• Use AI to point, and humans to prove. Use tools to sort and summarize, then confirm every fact against an original source.

Where a licensed investigator fits

A licensed investigator helps by collecting evidence at its source, documenting custody, interviewing the people behind a recording, establishing the real-world facts around a questioned file, and testifying about what they did. The principle is simple: a file cannot be cross-examined, but an investigator can.

When questioned digital evidence is part of a business dispute or an internal compliance review, see our business litigation investigations and our brief on compliance investigations in Florida business litigation.

This article is general information for attorneys and legal professionals. It is not legal advice. Decisions about admissibility, discovery and strategy belong to counsel.

References

1. eDiscovery Today, “Deepfake Videos and Images Lead to Terminating Sanctions,” discussing Mendones v. Cushman & Wakefield, Inc., No. 23CV028772 (Cal. Super. Ct. Sept. 9, 2025). https://ediscoverytoday.com/2025/09/25/deepfake-videos-and-images-lead-to-terminating-sanctions-ediscovery-case-law/
2. Robert Chesney and Danielle Keats Citron, “Deep Fakes: A Looming Challenge for Privacy, Democracy, and National Security,” California Law Review. https://www.californialawreview.org/print/deep-fakes-a-looming-challenge-for-privacy-democracy-and-national-security
3. Section 90.901, Florida Statutes. https://www.flsenate.gov/Laws/Statutes/2026/90.901
4. Advisory Committee on Evidence Rules, Report (May 2026). https://www.uscourts.gov/sites/default/files/document/advisory_committee_on_evidence_rules_may_2026.pdf
5. Sections 934.03 and 934.06, Florida Statutes. https://www.flsenate.gov/Laws/Statutes/2026/934.03 and https://www.flsenate.gov/Laws/Statutes/2026/934.06
6. Section 934.425, Florida Statutes. https://www.flsenate.gov/Laws/Statutes/2026/934.425
7. FDACS Division of Licensing, Private Investigation Licenses. https://www.fdacs.gov/Business-Services/Private-Investigation-Licenses
8. The Florida Bar, Ethics Opinion 24-1 (January 19, 2024). https://www.floridabar.org/etopinions/opinion-24-1/
9. Mata v. Avianca, Inc., 678 F. Supp. 3d 443 (S.D.N.Y. 2023), Opinion and Order on Sanctions. https://www.nhd.uscourts.gov/sites/default/files/pdf/Mata-v-Avianca-sanctions-order.PDF