Motion to Quash an Out-Of-State Subpoena in California

Protection from foreign subpoenas

When an out-of-state or foreign subpoena targets a California person, business, or tech platform, the key protection tool is a motion to quash. This allows California witnesses and anonymous online speakers to challenge invasive or improper discovery while the underlying case remains pending in an out-of-state jurisdiction.

How Motions to Quash work for out-of-state subpoenas

Under California’s Interstate and International Depositions and Discovery Act (California’s version of the UIDDA), an out-of-state or foreign-practicing attorney must first domesticate an out-of-state or foreign subpoena in California before it can be enforced here in California. Once that step occurs, any motion to quash must be filed in the California superior court in the county where the discovery is taking place, not in the foreign court.​

After service of the California subpoena, the witness, recipient platform, or an affected individual (including an anonymous online speaker whose identifying information is sought) can file a motion to quash the subpoena, asking the California court to invalidate, narrow, or condition the subpoena. The court then applies California procedural rules, and the substantive law of the foreign action, to decide whether the subpoena is appropriate.

Often, the out-of-state opposing party will hire California local counsel to domesticate and manage foreign subpoena motions if in-person attendance is required.

Grounds to Move to Quash out-of-state subpoenas

Even when the underlying case is pending in another state or country, California law provides robust defenses against overreaching discovery. Common grounds for a motion to quash foreign subpoenas translated into California subpoenas include:​

• Overbreadth and undue burden, such as requests for documents or data from California-based tech companies.

• Lack of relevance or proportionality to the foreign case’s claims.

• Privacy concerns under California law, particularly for consumers, employees, and sensitive personal records.

• First Amendment protections when the subpoena seeks identifying information for anonymous online speakers, where the plaintiff in the out-of-state case has not met the required burden for unmasking.​

In many matters, California courts have granted motions to quash or significantly narrowed subpoenas seeking identities or data connected to internet activity, preserving anonymity and limiting foreign discovery to what is truly necessary.​

Protecting anonymous online speakers from foreign subpoenas

Out-of-state litigants frequently use foreign subpoenas to try to unmask anonymous bloggers, reviewers, social media users, unnamed perpetrators of alleged fraud, and other online speakers whose data is held by California-based platforms. After those subpoenas are domesticated under the IIDDA, Doe defendants or third-party witnesses can file motions to quash in California—often under a pseudonym—arguing that the foreign party has not met constitutional standards or made a prima facie showing on its claims.​

Kronenberger Rosenfeld has extensive experience moving to quash such subpoenas, including those issued in cases pending outside California, and has obtained success on motions to quash as well as negotiated withdrawals of subpoenas without the need for full motion practice. These efforts have kept clients’ identities confidential, with some plaintiffs ultimately dismissing their subpoena after failing to justify unmasking.​

Foreign subpoenas and 28 U.S.C. §1782

Foreign tribunals and litigants sometimes use the federal foreign discovery statute, 28 U.S.C. §1782, to obtain discovery in the United States, including subpoenas served on California entities. When such a subpoena is issued and enforced through a federal court in California, affected individuals and entities can still challenge it through motions to quash directed at the California-issued subpoena.​

The analysis in these cases often overlaps with traditional motion to quash concepts—relevance, burden, and statutory limits—while accounting for international comity and the foreign tribunal’s needs.

Do you need a California attorney?

Because disputes over out-of-state and foreign subpoenas are decided in California courts, local counsel play a central role in protecting witnesses and anonymous speakers.​

A California attorney evaluating a motion to quash a subpoena can:

• Evaluate the domesticated California subpoena for procedural defects and overreach.

• File a motion to quash or modify in the appropriate superior or federal court.

• Coordinate strategy with out-of-state or foreign counsel so the California subpoena process supports the broader litigation goals.

Conversely, for out-of-state litigants seeking discovery from California, understanding that any challenge to a domesticated subpoena will play out in a California motion to quash proceeding is just as important as knowing how to obtain the subpoena in the first place.

Our team has represented clients in motions to quash subpoenas issued under the IIDDA and in federal California courts, defending privacy and anonymity in cross-border disputes. Contact our team today to discuss local counsel in a subpoena matter.