How to Authenticate Evidence in California: A Legal Guide

Authenticating evidence is a crucial step in ensuring documents, images, recordings, and other materials are admissible in court. Under the California Evidence Code, proving authenticity means showing an item is what it claims to be. Below, we explain the rules, common authentication methods, and best practices for personal injury or wrongful death litigation in San Diego.

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Legal Requirement: Evidence Code § 1400–1402

Under California Evidence Code § 1400, the proponent must introduce evidence sufficient to support a finding that a writing is what it claims to be—or use another lawful method to establish authenticity. Section 1401(a) further mandates that evidence must be authenticated before admission. The burden of proof is on the party offering the evidence. (Evid. Code § 403)

The court judge decides whether the threshold is met. If authentication is properly supported, the jury will then decide the weight and credibility of the evidence

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The Most Common Methods for Authenticating Evidence

California law permits multiple valid methods to authenticate evidence under Evidence Code §§ 1410–1421. The most common methods include:

1. ‍Witness Testimony: A person with personal knowledge—such as someone who created, handled, or observed the writing—can testify it’s genuine. (Evid. Code § 1413)‍
2. Declaration of Authenticity: A custodian of records may provide a written declaration certifying the authenticity of business records, commonly used for medical, billing, employment, or financial documents. This method is often more efficient than live testimony and can support admission under the business records exception to hearsay. (Evid. Code § 1561)‍
3. Admissions and Stipulations: If the opposing party admits the document’s authenticity or acts on it as genuine, no further proof is required. (Evid. Code § 1414)

Let's explore each of these methods in greater detail.

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1. Witness Testimony - A Person with Knowledge 

A writing may be authenticated by anyone who saw the writing made or executed. (Evid. Code § 1413) More broadly, a writing may also be authenticated by anyone with knowledge to lay a basic foundation for the evidence. For example, a witness can be asked the following questions to authenticate evidence:

1. Do you recognize what has been marked for identification as Exhibit "x"?
2. What is it?
3. How do you recognize it?
4. Is it true and accurate?

The witness does not have to have created or observed the creation of the evidence to authenticate it. (Evid. Code § 1411.)‍

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2. Declaration of Authenticity - A Custodian of Records

Subpoenaed records are required to be produced along with a declaration of authenticity. (Code Civ. Proc. § 2020.430.) A declaration of authenticity is an affidavit signed by the custodian of records certifying the authenticity of the business records. (Evid. Code § 1561.) Specifically, the affidavit must state the following: 

1. The affiant is the duly authorized custodian of the records or other qualified witness and has authority to certify the records.
2. The copy is a true copy of all the records described in the subpoena, or [...] the records were delivered to the attorney, the attorney’s representative, or deposition officer for copying at the custodian’s or witness’ place of business, as the case may be.
3. The records were prepared by the personnel of the business in the ordinary course of business at or near the time of the act, condition, or event.
4. The identity of the records.
5. A description of the mode of preparation of the records.

(Evid. Code § 1561.)

An affidavit that meets these requirements is admissible at trial to establish the authenticity of the records produced. (Evid. Code § 1562.) 

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3. Admissions and Stipulations - Opposing Counsel

Requests for Admission

There are two ways that a party admission can serve to authenticate a document. 

1. Behavior/Act of Admission: A writing may be authenticated by evidence that: (a) The party against whom it is offered has at any time admitted its authenticity; or (b) The writing has been acted upon as authentic by the party against whom it is offered. (Evid. Code § 1414)
2. Discovery: Requests for Admission can be served to obtain a party’s admission to the authenticity of evidence. (Code Civ. Proc. § 2033.060(g).) The evidence should be attached to the Request for Admission as numbered exhibits. The requests should say something like: “Admit to the genuineness of the document attached as Exhibit 1,” and so on. A California Judicial Counsel form can also be used, which states: “You are requested to admit that [...] the original of each of the following documents, copies of which are attached, is genuine.” (Form DISC-020)

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Stipulation by Parties

The parties routinely stipulate to the authenticity of evidence where there is no good faith dispute as to the authenticity. (Evid. Code § 1400.) 

A stipulation is an agreement between the parties that a document or thing is authentic, which is filed with the court before trial. A stipulation may say something like: “Documents produced to a party to this action by another party or a third party in response to compulsory process (e.g., subpoena, Request for Production) shall be deemed authentic for the purposes of this lawsuit, absent good cause.”‍

Generally, this is done as a way to save time at trial. You should not count on the other side stipulating as a means of establishing authenticity.

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Other Methods for Authenticating Evidence

Judicial Notice

Certain types of evidence (e.g., court files and records) may be authenticated by judicial notice. (Evid. Code. § 451, 452)

Self-Authenticating

Certain writings are presumed to be authentic (i.e., self-authenticating). These include:

• Deeds, mortgages, grants of easements (Evid. Code § 1451)
• Documents bearing the seal of a public entity (Evid. Code § 1452, Code Civ. Proc. § 1931)
• Documents bearing an official or corporate signature (Evid. Code § 145Corps. C. § 313)
• Regularly published newspapers (Evid. Code § 645.1) 
• Printed representations of computer information (Evid. Code § 1552, 1553)

Handwriting Genuineness

A writing may be authenticated by evidence of the genuineness of the handwriting of the maker. (Evid. Code § 1415.)

• ‍Lay Witness: A witness who is not otherwise qualified to testify as an expert may state his opinion whether a writing is in the handwriting of a supposed writer if the court finds that he has personal knowledge of the handwriting of the supposed writer. (Evid. Code § 1416.)
• Trier of Fact: The genuineness of handwriting, or the lack thereof, may be proved by a comparison made by the trier of fact. (Evid. Code § 1417.) ‍
• Expert Witness: The genuineness of writing, or the lack thereof, may be proved by a comparison made by an expert witness. (Evid. Code § 1418.)

Personally Known Reference

A writing may be authenticated by evidence that the writing contains matters that are unlikely to be known to anyone other than the claimed author. (Evid. Code § 1421)

Circumstantial Evidence

Evidence may also be authenticated by circumstantial evidence. The Evidence Code does not exhaustively list all means of authentication: “Nothing in this article shall be construed to limit the means by which a writing may be authenticated or proved.” (Evid. Code § 1410.) 

“Circumstantial evidence, content, and location are all valid means of authentication.” (People v. Gibson (2001) 90 Cal.App.4th 371, 383.) There are “innumerable ways in which a document may be authenticated by circumstantial evidence,” if the evidence is “sufficient to sustain a finding that it is the writing that the proponent of the evidence claims it is.” (McAllister v. George (1977) 73 Cal.App.3d 258, 262-263.)

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Practical Examples of Authentication

Emails

• The sender or recipient of the email can testify that they wrote or received it. 
• When the sender or recipient is unavailable, circumstantial evidence may be used, including email addresses, names, contents, and metadata. For example, the testimony of someone from the same business as the sender or recipient should be able to lay sufficient foundation to authenticate.

Photographs and Video

• The person who took a photograph or video can testify to its authenticity. 
• A witness who has been to the location or seen the object depicted in the photograph or video can testify that the photograph or video truly and accurately represents the location or object.  
• Where no one is qualified to authenticate a photograph or video from personal observation, a photograph or video may be authenticated by the aid of expert testimony. (People v. Beckley (2010) 185 Cal.App.4th 509, 515.)

Website Pages

• When a party places material (or authorizes it to be placed) in its website, it makes an admission of whatever the material says. The fact that it is on the party’s website makes it self-authenticating. (Wegner et al., Cal. Practice Guide: Civil Trials and Evidence (The Rutter Group 2014) ¶ 8:359.6, p. 8C-33.) 
• Websites may be authenticated by testimony from a witness about what he or she observed. What is on the website, at the time the witness views it, should be preserved in a form that can be presented in court. (In re K.B. (2015) 238 Cal.App.4th 989.) 
• It may be possible to admit archived versions of web site content, stored and available at a third party web site (e.g., Wayback Machine). It may be authenticated by a witness who previously saw or used the site. It may also be possible to obtain a declaration or witness to testify to the archive.

Social Media Posts

• The simplest way to authenticate a social media post is to get the person who posted it to admit that it is authentic. This can be established during a deposition or at trial.
• A witness who received, viewed, or downloaded the post may testify to its authenticity. 
• A forensic computer expert may search for the content themselves and describe their process in detail, including the technical details which make them believe that the post is authentic. 
• The social media posts may also be requested from a party in discovery, which should make them easier to authenticate.
• Lastly, the social media post can be subpoenaed from the social media service provider. However, social media companies are resistant to providing subpoenaed information.   

Surveillance Footage

• Surveillance footage can be authenticated by the testimony or supporting affidavits from technicians with personal knowledge of the surveillance system. The testimony should confirm that the witness was familiar with the recording system, it was functioning properly, he or she made a copy of the footage, and the subject footage is the same as the copy and was not altered in any way.  

Google Maps Images

• Google Map images can be authenticated by attaching them to a Request for Admission. 
• If the defense is not willing to stipulate to their authenticity, then the best practice (particularly for critical historical images) is to subpoena them from Google. Google will then produce them with a declaration of authenticity. 
• Alternatively, a witness may be able to authenticate the images if the witness has personal knowledge of the appearance of the location at the time the images were taken.  

Medical Records 

• Medical records are admissible as business records, provided a custodian of records or other duly qualified witness provides proper authentication to meet the foundational requirements of the business records hearsay exception.  
• Compliance with a subpoena may dispense with the need for a witness to establish the business records exception if the records are produced by the custodian or other qualified witness, together with a declaration of authenticity. 
• Absent a declaration of authenticity, a stipulation between the parties, or an admission to authenticity, the testimony of a qualified witness may be needed to authenticate the records. 

Physical Evidence

• Physical evidence, such as an accident vehicle or component part, is authenticated by demonstrating a continuous and unbroken chain of custody from collection at the scene to presentation in court. (People v. Riser (1956) 47 Cal. 2d 566, 580.) 
• Any destructive inspection or testing of physical evidence should be videotaped to maintain chain of custody.

Computer Data

• A printout of computer information or a computer program is presumed to be an accurate representation of the computer information. (Evid. Code § 1552; Ampex Corp v. Cargle (2005) 128 Cal.App.4th 1569, 1573.) 
• California law distinguishes between records that a computer generates on its own and records that a person inputs into the computer. The former, such as an automated time signature, is presumed to be authentic. (People v. Hawkins (2002) 98 Cal.App.4th 1428, 1450.)

Official Records 

• Various presumptions may be used to authenticate official records with an official seal or signature. (Evid. Code § 1450-1454.) 
• Official records include government documents, or documents filed with the government (e.g., Secretary of State). 
• There is also a presumption that official signatures are genuine. (Evid. Code § 1530, 1453.)

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Conclusion

In high-stakes cases like wrongful death or catastrophic injuries, authenticated documents—such as medical reports, photos, public documents, or correspondence—are essential for proving your case. Utilize proper authentication to ensure critical evidence survives objection.

Contact Hulburt Law Firm for further guidance on building a strong evidentiary foundation—and securing your key documents at trial.

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Conor Hulburt is a plaintiff’s trial attorney and founder of the Hulburt Law Firm in San Diego, California. Conor has recovered over $100 million on behalf of clients in catastrophic injury and wrongful death cases. He has successfully taken on Fortune 500 companies, major auto carriers, and government entities, including a landmark $28.1 million jury verdict in Quiroz v. Caltrans.