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Kathryn Cahoy

Kate Cahoy co-chairs the firm’s Class Action Litigation Practice Group and serves on the leadership committee for the firm’s Technology Industry Group. A highly skilled litigator, she defends clients in complex, high-stakes class action disputes, securing significant victories across various industries, including technology, entertainment, consumer products, and financial services. Kate also plays a key role in the firm’s mass arbitration defense practice. She regularly advises companies on the risks associated with mass arbitration and has a proven track record of successfully defending clients against these challenges.

Leveraging her success in class action litigation and arbitration, Kate helps clients develop strategic and innovative solutions to their most challenging legal issues. She has extensive experience litigating cases brought under California’s Section 17200 and other consumer protection, competition, and privacy laws, including the Sherman Act, California Consumer Privacy Act (CCPA), California Invasion of Privacy Act (CIPA), Wiretap Act, Stored Communications Act, Children’s Online Privacy Protection Act (COPPA), Video Privacy Protection Act (VPPA), along with common law and constitutional rights of privacy, among others.

Kate’s exceptional legal work has earned widespread recognition. The Daily Journal named her successful defense of Meta and Microsoft cases described below as among its Top Verdicts, recognizing some of the largest and most impactful verdicts in California.

Recent Successes:

Represented Meta (formerly Facebook) in a putative nationwide advertiser class action alleging violations under the California Unfair Competition Law (UCL) related to charges from allegedly “fake” accounts. Successfully narrowed claims at the pleadings stage, defeated class certification, opposed a Rule 23(f) petition, won summary judgment, and defended the victory on appeal to the Ninth Circuit. (Daily Journal, Top Verdicts of 2021. Law.com recognized Kate with a Litigator of the Week Shoutout.
Defeated a landmark class action lawsuit against Microsoft and OpenAI contending that the defendants scraped data from the internet for training generative AI services and incorporated data from users’ prompts, allegedly in violation of CIPA, the Computer Fraud and Abuse Act (CFAA), and other privacy and consumer protection laws. (Daily Journal, Top Verdicts of 2024.)

Kate regularly contributes to the firm’s blog, Inside Class Actions, and was recently featured in a Litigation Daily interview titled “Where Privacy Laws and Litigation Trends Collide.” In recognition of her achievements in privacy and antitrust class action litigation, the Daily Journal named her as one of their Top Antitrust Lawyers (2024), Top Cyber Lawyers (2022), and Top Women Lawyers in California (2026). Additionally, she received the Women of Influence award from the Silicon Valley Business Journal, was recognized by the Daily Journal as a Top Attorney Under 40, and also was named to Bloomberg Law's They've Got Next: The 40 Under 40 list.

On September 30, Governor Gavin Newsom signed SB 690, a significant new law aimed at curbing the wave of lawsuits and demand letters asserting “pen register” claims under the California Invasion of Privacy Act (“CIPA”).  The legislation eliminates the private right of action for pen register and trap-and-trace claims arising…

Continue Reading California Governor Signs SB 690, Eliminating Private Website-Based CIPA Pen Register Claims and Calling for Broader CIPA Reform

On August 28, 2026, the California Legislature passed SB 690, a significant bill aimed at curbing the flood of demand letters and lawsuits asserting “pen register” claims under the California Invasion of Privacy Act (“CIPA”). If enacted, the bill would eliminate the private right of action for website-based pen register claims and could affect many pending lawsuits filed since January 1, 2025.

Continue Reading California Legislature Passes CIPA Pen Register Reform Bill and Sends It to Governor

On July 1, 2026, a California legislative committee advanced amendments to SB 690 that would eliminate private suits asserting website-based “pen register” claims under the California Invasion of Privacy Act (“CIPA”), leaving enforcement exclusively to the California Attorney General.  The amendments come amid a surge of lawsuits and demand letters challenging the use of website technologies under the pen register provision, which the committee described as a “poster child for abusive lawsuits.”  According to the committee analysis, “[b]ecause the potential liability can be staggering,” businesses often settle quickly, thereby “encouraging vexatious litigants to continue blasting out demand letters.”

Continue Reading California Legislature Advances Bill Targeting Wave of CIPA Pen Register Lawsuits

On April 1, 2026, the Seventh Circuit in Clay v. Union Pacific Railroad Company held that an amendment to the Illinois Biometric Information Privacy Act (BIPA), limiting damages to a per-person basis, applies retroactively to cases pending when the amendment was enacted in 2024. This decision limits the potential statutory damages plaintiffs may obtain for pending BIPA cases.

Continue Reading Seventh Circuit Holds that BIPA Amendment Applies Retroactively

Last week, the Third Circuit affirmed dismissal of a putative class action asserting that defendant Quest Diagnostics violated the California Invasion of Privacy Act (“CIPA”) and the Confidentiality of Medical Information Act (“CMIA”) by employing a website pixel to track and collect data about their website activity for advertising purposes.

Continue Reading Third Circuit Affirms Dismissal of CIPA and CMIA Claims

In a win for businesses using third-party technologies to power their websites, a California federal court applied the Ninth Circuit’s recent decision in Popa v. Microsoft Corporation to dismiss a “pen register” claim brought under the California Invasion of Privacy Act (“CIPA”) for lack of Article III standing.  Khamooshi v. Politico LLC, No. 24-cv-07836-SK, 2025 WL 2822879 (N.D. Cal. Oct. 2, 2025).  “As in Popa,” the Khamooshi court held that the plaintiffs—who alleged the collection of their device type, browser type, and “device fingerprints”—“identifie[d] no embarrassing, invasive, or otherwise private information collected,” as required to establish an Article III injury. 

Continue Reading Court Applies Popa to Dismiss CIPA Pen Register Claim for Lack of Article III Standing

“Session replay” software is one of many website analytics tools targeted in wiretapping suits under the California Invasion of Privacy Act (“CIPA”).  Last month, a California federal court confirmed one of the many reasons why the use of this software does not violate CIPA section 631: A defendant cannot “read” (or attempt to read) session replay data “in transit,” as CIPA requires, because “events recorded by” this software “do not become readable content until after they are stored and reassembled into a session replay.”  Torres v. Prudential Financial, Inc., 2025 WL 1135088 (N.D. Cal. Apr. 17, 2025). 

Continue Reading Court Grants Summary Judgment: Website Vendor Cannot Read “Session Replay” Data “In Transit” Under CIPA

Does a plaintiff’s use of a website constitute consent to a privacy policy linked in the website’s footer?  A Pennsylvania federal court answered yes in Popa v. Harriet Carter Gifts, Inc., 2025 WL 896938 (W.D. Pa. Mar. 24, 2025), granting summary judgment in favor of an online retailer (Harriet Carter Gifts) and its marketing partner (NaviStone) accused of collecting data about plaintiff’s website visit in violation of the Pennsylvania Wiretapping and Electronic Surveillance Control Act (“WESCA”).

Continue Reading Implied Consent to Privacy Policy in Webpage Footer Forecloses Website Wiretapping Claim

Early this month, a Northern District of California judge dismissed, with prejudice, a putative class action complaint asserting five privacy-related causes of action, concluding the “issue of consent defeat[ed] all of Plaintiffs’ claims.”  Lakes v. Ubisoft, Inc., –F. Supp. 3d–, 2025 WL 1036639 (N.D. Cal. Apr. 2, 2025).  Specifically, the Court dismissed plaintiffs’ claims under the (1) Video Privacy Protection Act (“VPPA”); (2) Federal Wiretap Act; (3) California Invasion of Privacy Act (“CIPA”) § 631; (4) common law invasion of privacy; and (5) Article I, Section 1 of the California Constitution. 

Continue Reading California Court Holds Plaintiffs’ Consent Defeats Claims Involving Use of Website Pixel

A fan of celebrity LL Cool J filed a wiretapping suit against Community.com (“Community”), claiming that Community accessed her text message to LL Cool J in violation of the federal Wiretap Act and the California Invasion of Privacy Act (“CIPA”).  In an unpublished opinion highlighting that Section 632 of CIPA does not protect communications that are by nature a recorded medium, the Ninth Circuit affirmed dismissal of the plaintiff’s claims. See Boulton v. Community.com, Inc., No. 23-3145, 2025 WL 314813 (9th Cir. Jan. 28, 2025).

Continue Reading Ninth Circuit Affirms Dismissal of CIPA and Wiretap Act Claims Against Celebrity Platform