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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 (2023). 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.

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

“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”

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

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

Website analytics and advertising tools, such as pixels, are regularly targeted in lawsuits brought under various wiretap laws, including the federal Wiretap Act and the California Invasion of Privacy Act (“CIPA”).  We cover significant developments and trends in website wiretapping lawsuits on Inside Class Actions.  Over the last several

Continue Reading Website Wiretapping Litigation: Recent Decisions and Developments

Websites cannot load without the transmission of an IP address, which tells websites where to deliver the webpages displayed on a user’s browser.  Yet a number of lawsuits have started challenging this routine transmission of IP addresses under a lesser-known provision of the California Invasion of Privacy Act (“CIPA”) that

Continue Reading Court Holds CIPA’s Pen Register Provision Does Not Impose Liability for “What Makes the Internet Possible.”

An Illinois federal court has dismissed a proposed class action alleging X Corp. violated the state’s Biometric Information Privacy Act (“BIPA”) through its use of PhotoDNA software to create “hashes” of images to scan for nudity and related content. The court held that Plaintiff failed to allege that the hashes identified photo subjects and therefore failed to allege that the hashes constituted biometric identifiers. Martell v. X Corp., 2024 WL 3011353, at *4 (N.D. Ill. June 13, 2024).

BIPA prohibits private entities from collecting or capturing “a person’s or a customer’s biometric identifier or biometric information” without first obtaining the subject’s informed consent, among other requirements. 740 ILCS 14/15(b). BIPA defines “biometric identifier” as “a retina or iris scan, fingerprint, voiceprint, or scan of hand or face geometry” and defines “biometric information” as any information “based on an individual’s biometric identifier used to identify an individual.” 740 ILCS 14/10.

In dismissing the complaint, the court agreed with X’s arguments that Plaintiff failed to plausibly allege (1) that the PhotoDNA software collects scans of facial geometry and (2) that the hashes identified photo subjects. First, the court rejected Plaintiff’s “conclusory” assertion that the creation of a hash from a photo that includes a person’s face “necessitates” creating a scan of facial geometry, saying, “The fact that PhotoDNA creates a unique hash for each photo does not necessarily imply that it is scanning for an individual’s facial geometry when creating the hash.” Id. at *2. The court distinguished Plaintiff’s allegation from those that withstood dismissal in a different case in which the plaintiff alleged that scans of photos “located her face and zeroed in on its unique contours to create a ‘template’ that maps and records her distinct facial measurements.” Id. at 3 (quoting Rivera v. Google Inc., 238 F. Supp. 3d 1088, 1091 (N.D. Ill. 2017)).Continue Reading Illinois Federal Court Dismisses BIPA Suit Against X, Holding “Biometric Identifiers” Must Identify Individuals

Only one claim survived dismissal in a recent putative class action lawsuit alleging that a pathology laboratory failed to safeguard patient data in a cyberattack.  See Order Granting Motion to Dismiss in Part, Thai v. Molecular Pathology Laboratory Network, Inc., No. 3:22-CV-315-KAC-DCP (E.D. Tenn. Sep. 29, 2023), ECF 38.

Continue Reading All but One Claim in Pathology Lab Data Breach Class Action Tossed on Motion to Dismiss

Recent months have seen a growing trend of data privacy class actions asserting claims for alleged violations of federal and state video privacy laws.  In this year alone, plaintiffs have filed dozens of new class actions in courts across the country asserting claims under the federal Video Privacy Protection Act

Continue Reading Emerging Trends: Renewed Wave of Video Privacy Class Actions

A recent class action refiled in federal court against Shopify highlights a growing trend of lawsuits against companies related to the theft of cryptocurrency, particularly as a result of internal company threats.  See Forsberg et al v. Shopify, Inc. et al, 1:22-cv-00436 (D. Del.).  Despite not itself being a
Continue Reading Companies Increasingly Facing Class Actions Connected to Cryptocurrency Theft

An Illinois federal district court recently rejected dismissal of Illinois Biometric Information Privacy Act (“BIPA”) claims in In re Clearview AI, Inc., Consumer Privacy Litigation, No. 21-cv-135 (N.D. Ill.).  The Clearview plaintiffs alleged that Clearview violated their privacy rights without their knowledge and consent by scraping more than three
Continue Reading Court Rejects Dismissal of Illinois Biometric Information Privacy Act Against Clearview AI in Pending Multidistrict Litigation