Rule 3.764.Motion to certify or decertify a class or amend or modify an order certifying a class

Division 7. Civil Case Management · Chapter 6. Management of Class Actions · Last amended 2026 · Last verified July 29, 2026

In one sentenceRule 3.764 lets any party move to certify a class, certify subclasses, amend or modify a certification order, or decertify a class, and it sets the deadlines, page limits, and required supporting papers for that motion.

Full Text of Rule 3.764

Text sizeJump to: (a) (b) (c) (d) (e)

(a) Purpose Any party may file a motion to:

(1) Certify a class;

(2) Determine the existence of and certify subclasses;

(3) Amend or modify an order certifying a class; or

(4) Decertify a class.

(b) Timing of motion, hearing, extension, deferral A motion for class certification should be filed when practicable. In its discretion, the court may establish a deadline for the filing of the motion, as part of the case conference or as part of other case management proceedings. Any such deadline must take into account discovery proceedings that may be necessary to the filing of the motion.

(1) Time for service of papers Notice of a motion to certify or decertify a class or to amend or modify a certification order must be served on all parties to the action and filed at least 34 calendar days before the date set for hearing. Any opposition to the motion must be served and filed at least 20 calendar days before the noticed or continued hearing, unless the court for good cause orders otherwise. Any reply to the opposition must be served and filed at least 11 calendar days before the noticed or continued date of the hearing, unless the court for good cause orders otherwise. The provisions of Code of Civil Procedure section 1005 otherwise apply.

(2) Length of papers An opening or responding memorandum filed in support of or in opposition to a motion for class certification must not exceed 20 pages. A reply memorandum must not exceed 15 pages. The provisions of rule 3.1113 otherwise apply.

(3) Documents in support The documents in support of a motion for class certification consist of the notice of motion; a memorandum; evidence in support of the motion in the form of declarations of counsel, class representatives, or other appropriate declarants; and any requests for judicial notice.

(4) Documents in opposition The documents in opposition to the motion consist of the opposing party’s memorandum; the opposing party’s evidence in opposition to the motion, including any declarations of counsel or other appropriate declarants; and any requests for judicial notice. (Subd (c) amended effective January 1, 2026; previously amended effective January 1, 2007.)

(d) Presentation of evidence Evidence to be considered at the hearing must be presented in accordance with rule 3.1306. (Subd (d) amended effective January 1, 2007.)

(e) Stipulations The parties should endeavor to resolve any uncontroverted issues by written stipulation before the hearing. If all class issues are resolved by stipulation of the named parties and approved by the court before the hearing, no hearing on class certification is necessary.

End

Plain-English Summary

Rule 3.764 hands any party — not just the plaintiff — the tools to move the class question forward, whether that means asking the court to certify a class, carve out subclasses, adjust a certification order already in place, or undo certification altogether. There is no fixed filing deadline; the motion should come when it makes practical sense, though the court can set one during case management, and any deadline it sets has to leave room for the discovery the motion will need.

The filing schedule for a certification motion runs longer than an ordinary motion: notice goes out at least 34 calendar days before the hearing, opposition papers are due at least 20 days before, and a reply follows at least 11 days before, unless the court allows a different schedule for good cause. Code of Civil Procedure section 1005 fills in anything the rule does not cover. Page limits keep the briefing manageable — 20 pages for an opening or opposing memorandum, 15 for a reply — and rule 3.1113 governs the rest of the formatting. The moving papers consist of the notice of motion, a memorandum, supporting declarations, and any requests for judicial notice; the opposing papers mirror that structure from the other side.

Any evidence offered at the hearing has to come in the way rule 3.1306 requires. And the rule pushes the parties toward agreement before they ever get to a hearing: if they can resolve the class issues by stipulation and the court signs off before the hearing date, no hearing is needed at all.

Frequently Asked Questions

Who can file a motion to certify or decertify a class?

Any party. Rule 3.764 is not limited to plaintiffs — a defendant can move to certify subclasses or to decertify a class already certified.

How far in advance must a class certification motion be filed?

Notice must be served and filed at least 34 calendar days before the hearing. Opposition is due at least 20 days before the hearing, and a reply at least 11 days before, unless the court orders a different schedule for good cause.

Is there a page limit on class certification briefing?

Yes. An opening or opposing memorandum cannot exceed 20 pages, and a reply memorandum cannot exceed 15 pages.

Can the parties avoid a certification hearing altogether?

Yes. If the named parties resolve all class issues by stipulation and the court approves the stipulation before the hearing, no hearing on class certification is necessary.

Does the court set an early, fixed deadline for filing a certification motion?

Not automatically. The motion should be filed when practicable, though the court may set a deadline as part of case management, and that deadline has to account for the discovery the motion needs.

Amendment History

Rule 3.764 amended January 1, 2026; adopted as rule 1854 effective January 1, 2002; previously amended and renumbered effective January 1, 2007.

Source & verification. Rule text is reproduced verbatim from the Judicial Council of California. Adopted by the Judicial Council of California. Last verified July 29, 2026. · Official source

Also known as: motion to certify a class californiamotion to decertify a class actionclass certification motion filing deadlinespage limit class certification briefing