For years I've heard grumbling about Civil Local Rule 23-3 of the United States District Court for the Central District of California.  I may have been been responsible for some of that grumbling myself.  If you haven't run into this rule, Local Rule 23-3 requires the filing of a class certification motion within 90 days of the commencement of the action.  While many judges would accept stipulations to waive the rule, some did not.  In ABS Entertainment Inc. v. CBS Corp. (9th Cir. Aug. 20, 2018), the Ninth Circuit finally addressed this Local Rule in a published opinion (I believe there was commentary in an unpublished opinion a number of years ago):

Central District of California Local Rule 23-3 sets a strict 90-day time frame from the filing of a complaint to the motion for class action certification. This bright line rule is in direct contrast to the flexibility of the Federal Rule, which calls for a determination on class certification “[a]t an early practicable time after a person sues or is sued as a class representative.” Fed. R. Civ. P. 23(c)(1)(A). That flexible approach makes sense. The class action determination can only be decided after the district court undertakes a “rigorous analysis” of the prerequisites for certification. Wal-Mart Stores, Inc. v. Dukes, 564 U.S. 338, 350–51 (2011) (quoting Gen. Tele. Co. of SW v. Falcon, 457 U.S. 147, 161 (1982)). To undertake that analysis may require discovery. Kamm v. Cal. City Dev. Co., 509 F.2d 205, 210 (9th Cir.1975) (“The propriety of a class action cannot be determined in some cases without discovery;” “To deny discovery in [such cases] would be an abuse of discretion.”).

The district court’s actions here demonstrate the impracticability of the 90-day limit, particularly in combination with the district court’s summary and unexplained denial of the parties’ joint stipulation to extend the 90-day deadline based on the need for pre-certification discovery. See Barbara J. Rothstein & Thomas E. Willging, Federal Judicial Center, Managing Class Action Litigation: A Pocket Guide for Judges 9 (3d ed. 2010) (“Considering [Fed. R. Civ. P. 23(c)(1)], you should feel free to ignore local rules calling for specific time limits; such local rules appear to be inconsistent with the federal rules and, as such, obsolete.”); Federal Judicial Center, Manual for Complex Litigation, Fourth § 21.133 (“Some local rules specify a short period within which the plaintiff must file a motion to certify a class action. Such rules, however, may be inconsistent with Rule 23(c)(1)(A)’s emphasis on the parties’ obligation to present the court with sufficient information to support an informed decision on certification. Parties need sufficient time to develop an adequate record.”).

Although the district court’s application and interpretation of its Local Rules is entitled to “a large measure of discretion,” Lance, Inc. v. Dewco Servs., Inc., 422 F.2d 778, 784 (9th Cir. 1970), Local Rules cannot be incompatible with Federal Rules. Fed. R. Civ. P. 83(a)(1). We conclude that the bright-line of Local Rule 23-3 is incompatible with Federal Rule of Civil Procedure 23.

Slip op., at 49-50.  I only wonder whether the inclusion of this discussion at the end of a massive copyright opinion will give it more attention -- perhaps enough to lead to a repeal of Local Rule 23-3 entirely -- or less because it will get lost at the end of this unusually long opinion.