How to File an Opposition to an Anti-SLAPP Motion in California

To file an opposition to an anti-SLAPP motion in California, you must serve and file a written opposition with supporting declarations and admissible evidence at least nine court days before the hearing, showing either that the defendant’s conduct is not protected activity under Code of Civil Procedure section 425.16 or that you have a probability of prevailing on each challenged claim. Lose, and the court dismisses those claims and orders you to pay the defendant’s attorney’s fees.¹

What You Have to Prove

The court runs a two-step analysis, and your opposition has to address both.

Step one belongs to the defendant. They must show that your lawsuit targets conduct protected by the anti-SLAPP statute: statements made in connection with official proceedings, statements in public forums about issues of public interest, or other activity tied to petition or free-speech rights on a public issue.¹ If the conduct doesn’t fit, the motion fails no matter how weak your case is. Argue this whenever the facts let you.

Step two shifts to you. You must show a “probability of prevailing” on each challenged claim.¹ You aren’t proving your case. You’re putting enough admissible evidence in front of the court that a reasonable jury could find in your favor on every element. The court takes your evidence at face value and doesn’t weigh credibility. The bar is low, but it demands real evidence, not the allegations in your complaint.

The Deadline and How to Serve

Under Code of Civil Procedure section 1005, your opposition papers must be filed with the court and served on the defendant at least nine court days before the hearing. Court days are Monday through Friday, excluding judicial holidays. Count backward from the hearing, skipping the hearing day itself.

The hearing is supposed to be set within 30 days after the motion is served, though court congestion often pushes it later.¹ Either way, expect very little time between receiving the motion and your deadline. Start gathering evidence the day the motion arrives.

California courts observe several holidays beyond the federal calendar, including Lincoln’s Birthday, César Chávez Day, Juneteenth, Native American Day, and the day after Thanksgiving. Miscounting one of them can blow your deadline.

Serve the defendant’s attorney by the method your case requires (electronic service, mail, or personal delivery), file everything with the court, and include a proof of service. Most California courts accept e-filing, and many require it.

The Documents in a Complete Opposition

An opposition isn’t a single brief. It’s a package.

Opposition brief. Your legal arguments on both steps: that the conduct isn’t protected activity, and that your evidence establishes a probability of prevailing. Cite the statutes, the case law, and the specific declarations and exhibits.
Declarations. Sworn statements from you and each witness with firsthand knowledge, signed under penalty of perjury, with exhibits attached and identified.
Compendium of evidence. An organized collection of the documentary exhibits referenced in your brief and declarations, labeled clearly, with a table of contents if it’s substantial.
Request for judicial notice. Optional. Use it for court records, public records, or other facts a court can officially recognize.
Evidentiary objections. If the defendant’s motion relies on hearsay, unauthenticated documents, or speculation, file written objections identifying each problem. Knocking out key pieces of the defendant’s evidence can move the analysis.

Judges deciding these motions are matching your evidence against the elements of each claim. If they can’t quickly find the supporting exhibit or declaration, your opposition is weaker for it.

Building Admissible Evidence Under the Discovery Stay

Your evidence has to be admissible at trial, not just persuasive on paper. This is where most oppositions succeed or fail.

Declarations carry the weight. Each one should walk through the specific facts supporting your claims rather than repeat legal conclusions from the complaint. In a contract case, that means when the agreement was made, what each side promised, how the defendant fell short, and what it cost you. Documentary evidence (emails, texts, contracts, invoices, photographs, recordings) reinforces the declarations. Attach these as exhibits and have the witness identify each one and explain its significance.

Every exhibit needs foundation. A declaration that says “attached is an email from the defendant” without explaining how the witness knows it’s authentic hands the defendant an easy objection. Say who sent it, when, how the witness received it, and why they recognize it.

Complicating all of this: filing an anti-SLAPP motion automatically stays discovery until the court rules.¹ No interrogatories, no document requests, no depositions. You’re working with what you already have.

There’s an escape valve. The statute lets you file a noticed motion asking the court to permit specific, limited discovery on a showing of good cause.¹ Identify exactly what you need, explain why it’s essential to your opposition, and show it isn’t available another way. Broad fishing expeditions get denied. If key evidence sits entirely in the defendant’s hands, pursue this motion early, and know the court may not rule quickly enough to help.

Statutory Exemptions That Can End the Motion

Before slogging through the merits analysis, check whether your case qualifies for an exemption under Code of Civil Procedure section 425.17. Two matter most.

Public Interest Exemption

The anti-SLAPP statute doesn’t apply to actions brought solely in the public interest or on behalf of the general public when all three of these conditions are met:

You aren’t seeking anything beyond what the general public or your class would receive (attorney’s fees or penalties don’t disqualify you).
A win would enforce an important right affecting the public interest and confer a significant benefit on the general public or a large class.
Private enforcement is necessary and places a disproportionate financial burden on you compared to your personal stake.

All three must be satisfied at once.²

Commercial Speech Exemption

Section 425.17 also blocks businesses from using anti-SLAPP motions to shield their sales activity. It applies when the defendant is primarily in the business of selling goods or services and the lawsuit challenges factual representations about the defendant’s or a competitor’s products made to buyers, potential customers, or people likely to influence purchasing decisions.² If you’re suing a company for false statements it made to sell products, this exemption may take the motion off the table entirely.

The Hearing and the Ruling

At the hearing, the judge reviews the motion, your opposition, and any reply. Both sides usually get oral argument. The court can deny the motion (and your case proceeds), grant it (and the targeted claims are dismissed), or split the ruling so some claims survive and others don’t.

Filing no opposition doesn’t automatically hand the defendant a win. They still have to satisfy step one. But without evidence in the record, you will almost certainly lose step two, because the court has nothing to evaluate on probability of prevailing. Skipping the opposition is effectively conceding.

Fees If You Lose, Fees If the Motion Was Frivolous

If the defendant wins, California law requires you to pay their attorney’s fees and costs for the motion. It isn’t discretionary. Awards can run from tens of thousands of dollars in simple cases to six figures in complex ones, owed even if your case had some factual basis but fell short of the prima facie threshold. One narrow carve-out: claims brought under California’s public records or open meetings laws aren’t subject to anti-SLAPP fee shifting, though those laws have their own fee provisions.¹

Fees run in the other direction too, but the standard is harder. If the court finds the anti-SLAPP motion was frivolous or filed solely to cause unnecessary delay, you can recover your fees and costs.¹ Under section 128.5, “frivolous” means totally and completely without merit or brought solely to harass.³ Losing isn’t the same as frivolous. But if the motion was transparently meritless and looks designed just to trigger the discovery stay, raise it.

Appeals Can Freeze the Case

In California state court, either side can appeal the ruling on an anti-SLAPP motion immediately, without waiting for a final judgment.¹

That matters for planning. If the court denies the motion and your case survives, the defendant can appeal right away, and the appeal typically stays the whole lawsuit, potentially freezing everything for a year or longer. Budget for it. If the court grants the motion, you have the same immediate appeal right, and the appellate court reviews both steps of the analysis.

Federal court is different. The Ninth Circuit held in 2025 that denying an anti-SLAPP motion is not immediately appealable under the collateral order doctrine, even when California’s anti-SLAPP law supplies the standard.⁴ If your case is in federal court, the appeal picture looks quite different from what state court would give you.

1
California Legislative Information. California Code CCP 425.16 – Special Motion to Strike
2
California Legislative Information. California Code CCP 425.17 – Exemptions to Anti-SLAPP Law
3
California Legislative Information. California Code CCP 128.5 – Sanctions for Frivolous Actions
4
United States Court of Appeals for the Ninth Circuit. Gopher Media LLC v. Melone