Drummer v. CoStar Group, Inc.

Published by Crandall Consulting · Informational litigation intelligence · Last substantive update: October 7, 2026

Docket / citation: 26-1652

Summary

The U.S. Chamber filed an amicus brief in the Ninth Circuit appeal Drummer v. CoStar Group, Inc. (docket 26-1652), arguing that collecting and transmitting IP addresses necessary for basic internet functioning does not constitute an Article III injury and that the California Invasion of Privacy Act is limited to telephone communications. The matter is pending on appeal in the Ninth Circuit; the amicus brief was filed June 4, 2026.

Litigation Status

Status, direction, and weight describe how tracked public sources characterize this matter as of our last review — they are informational classifications, not legal assessments.

Procedural Posture

Interlocutory appeal pending before the Ninth Circuit; U.S. Chamber filed an amicus brief (filed 2026-06-04) urging the court to hold that the collection and transmission of IP addresses is not an Article III injury and that the California Invasion of Privacy Act is limited to telephone communications.

Significance

Generally viewed as defense-favorable. Characterizations of significance describe how the matter has generally been discussed in tracked public sources; individual holdings are often narrow, procedural, or fact-specific, and this page does not state or imply broader holdings than the sources support.

What This Page Does and Does Not Say

This page reports what our tracked public sources say about this matter — including, where identified, the procedural posture (for example, a ruling on a motion to dismiss is not a final merits decision). It does not report legal conclusions beyond those sources, does not predict outcomes, and does not constitute legal advice.

Technologies at Issue

• IP addresses
• website tracking/analytics
• targeted advertising
• pen-register/trap-and-trace technology (as framed in statute)
• internet communications

Third parties named or identified in tracked sources: CoStar Group, Inc..

Statutes Invoked

• Cal. Penal Code §§ 638.50–638.53 (CIPA pen-register/trap-and-trace provisions); Cal. Civ. Code §§ 1798.100, 1798.110, 1798.140 (CCPA/CPRA provisions cited) — all-party consent · private right of action
• California Invasion of Privacy Act — all-party consent · private right of action

Claims Asserted

Claims identified in tracked public sources; pleadings may include additional or amended claims.

• California Invasion of Privacy Act (CIPA) claim for unlawful collection/transmission of IP addresses
• Article III standing
• California Invasion of Privacy Act claim

What This Matter May Mean for Website Operators

California Invasion of Privacy Act (CIPA) is an all-party consent statute with a private right of action. Consent standard and private enforceability are the structural features that most shape where website tracking claims are filed and how they are valued.

For operators using similar technologies, the recurring factual questions in matters like this one are what page URLs and query strings analytics tools share with third parties. Our scanner tests these behaviors empirically.

Because this matter is pending, anything reported here is procedural — allegations and interim rulings, not final determinations.

Detection of a similar technology on a website is an informational risk indicator, not a legal conclusion, and nothing in this section is legal advice.

Related Intelligence

Sources

• U.S. Chamber Amicus Brief (Drummer v. CoStar Group, Inc.) — U.S. Chamber Litigation Center / U.S. Chamber of Commerce · Tier A (Primary authority) · 2026-06-04
• Drummer v. CoStar Group, Inc. (Ninth Circuit interlocutory appeal re: IP-address standing) — U.S. Chamber of Commerce · Tier D (Industry data) · 2026-06-04

About This Page

Publisher: Inspection-Ready Institute, Inc. (DBA Crandall Consulting), an independent website compliance and risk consultancy. We are not a law firm and nothing on this page is legal advice.

How this content is produced: Facts are extracted from publicly available sources — court and government materials, recognized legal press, professional analysis, and industry reports — by our litigation intelligence engine, stored with full source provenance, and rendered from the database. Risk guidelines are computed by a deterministic formula, never by an AI model directly. See the full methodology.

Limitations: Counts labeled "Tracked" reflect matters identified in our source set and are not official court statistics. We report what courts decided and did not decide; we do not predict outcomes.

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