How to Protect Yourself When Signing a Witness Affidavit in California

Detailed answer — what you need to know and do

What an affidavit is and why it matters

An affidavit is a written statement of facts that you sign under oath or under penalty of perjury. Courts, insurers, or attorneys may use affidavits as evidence. Because you sign under oath (or use a sworn declaration), intentionally providing false information can expose you to perjury or other criminal penalties. See Penal Code §118 for the law on false statements under oath, and for civil filings many people use unsworn declarations permitted by Code of Civil Procedure §2015.5.

Before you sign: practical steps to protect yourself

• Read every word. Do not sign until you have read the entire affidavit. Ask for time to review.
• Speak only to facts you personally observed. Give concrete details: where you were, approximate distance from the vehicles, what each driver did, colors/makes of vehicles, time, lighting, weather, and any sounds (horns, screeching). Avoid hearsay (what someone else said happened) and speculation about causes or driver intent.
• Use plain, factual language. Prefer statements like “I saw,” “I observed,” or “The red sedan was going about X mph relative to traffic” rather than “I think the driver was negligent.” Legal conclusions are for lawyers and the judge or jury.
• Correct errors clearly. If a draft contains inaccuracies, mark them, cross out clearly, add a corrected sentence, and initial and date the changes. If a notarization is required, get the corrected final page notarized.
• Keep a signed copy. Obtain and keep a complete copy of what you signed (including any exhibits or photos attached).
• Don’t admit fault or apologize. Even an offhand “I’m sorry” can be used as an admission in later proceedings.
• Avoid social media and discussions. Don’t post or discuss the accident online or with others who might repeat what you said. Preserve your credibility.

If someone hands you a pre-prepared affidavit

You may be asked to sign an affidavit prepared by a lawyer, insurance adjuster, or another party. That is allowed, but take these precautions:

• Insist on time to read it in full.
• Refuse to sign if it contains statements you did not observe or that are inaccurate.
• Request modifications or cross-outs for anything you did not say exactly as written. Make sure any changes are initialed and dated by you, and re-reviewed before notarization or signing under penalty of perjury.
• If you feel pressured or threatened, stop and leave; consider contacting law enforcement or an attorney.

Subpoenas, court testimony, and legal obligations

If the court subpoenas you to testify, you must appear and tell the truth. An affidavit may be used in court, but testimony under oath carries the same obligations. If you have concerns about testifying (for safety or other reasons), consult an attorney promptly about protective measures or motions that might be available.

Criminal exposure: perjury and related offenses

Intentionally making a false material statement under oath or in a sworn affidavit can lead to criminal charges under California law. For the statute defining false statements under oath, see Penal Code §118. For the use of declarations under penalty of perjury (an alternative to notarized affidavits in many civil matters), see Code of Civil Procedure §2015.5.

When to consult an attorney

Consider seeking legal advice if:

• You are unsure what you actually saw or your memory is uncertain.
• Any portion of the affidavit asks you to admit fault or to estimate culpability.
• Someone pressures you to sign quickly or refuses to allow edits.
• You received a subpoena or believe criminal charges could follow.

Common safe phrasing for witness statements

Examples of neutral, factual phrasing you can use inside an affidavit:

• “On [date] at approximately [time] I was standing/driving at [location].”
• “I observed a [color, make] vehicle in the [lane description] traveling [approximate speed if you can estimate].”
• “I saw the [describe specific action: e.g., ‘vehicle run the red light’, ‘make a left turn without signaling’, ‘brake suddenly’].”
• “I did not see the driver using a phone or I did not notice any signs that the driver was impaired.” (Only include what you actually observed.)

Record-keeping and evidence preservation

Take photos of the scene and any damage, note contact information for other witnesses, and preserve any audio or video (dashcam, phone video, traffic cameras). Record your observations in writing as soon as possible while your memory is fresh. These contemporaneous notes strengthen the accuracy and credibility of your later affidavit.

Helpful Hints

• Ask who will use the affidavit and how it will be submitted (insurance claim, court, police report).
• Refuse to sign blank or partially completed forms.
• If asked to sign at the scene, say you will review and sign later after you read the full document.
• Initial any handwritten changes, and if pages were added or removed, note that on the document before signing.
• Keep calm and avoid volunteer opinions about fault or legal conclusions.
• If unsure about legal consequences, a single phone call to a local attorney can clarify your obligations and risks before you sign.

Quick checklist before signing an affidavit

1. Read the entire document aloud or silently.
2. Confirm every factual statement matches your memory.
3. Correct or delete inaccurate statements; initial changes.
4. Make sure the affidavit does not require you to speculate or give legal conclusions.
5. Get a signed and dated copy for your records.