California Code of Civil Procedure section 2019.210 provides that, before the plaintiff in a trade secret lawsuit may commence discovery relating to its alleged trade secret(s), it must “identify the trade secret with reasonable particularity.” This provision provides defendants with a powerful tool, preventing a plaintiff from alleging the misappropriation of trade secrets in vague or generalized terms, and then back-filing the allegations after discovery starts. The Ninth Circuit has yet to rule on its applicability in federal court, and California district courts conducting an Erie analysis are split on the issue. However, even district courts that hold section 2019.210 does not apply often require plaintiffs, pursuant to a federal court’s inherent Rule 26 powers, to disclose their trade secrets with particularity before obtaining discovery from defendants. In sum, section 2019.210 can be a powerful tool, and in deciding whether to file a trade secret action in federal or state court, plaintiffs should expect that they will have to disclose their trade secrets with “reasonable particularity” – either pursuant to section 2019.210 or the court’s Rule 26 order – before they can begin discovery.