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Karl Stephen Kronenberger

Internet Attorney at San Francisco, CA

5.0   1 review
  • State Years
    New York - NY 15 years
    California - CA 20 years
    Georgia - GA 25 years
    Ohio - OH 30 years
  • Licensed for 15 years
    State NY
    Acquired 2008
    Currently Registered No misconduct found
  • Licensed for 20 years
    State CA
    Acquired 2003
    Active No misconduct found
  • Licensed for 25 years
    State GA
    Acquired 1998
    Active Member in Good Standing No misconduct found
  • Licensed for 30 years
    State OH
    Acquired 1993
    Active No misconduct found

We have not found any instances of professional misconduct for this lawyer.

About Karl

Learn Karl’s areas of practice.


A seasoned litigator, Karl has tried more than 20 jury trials and many more bench trials, and he regularly handles complex digital media and technology law issues, such as internet trademark and copyright infringement, spam litigation defense, internet defamation and false advertising, cybersquatting, FTC lawsuits, website agreements and privacy disputes. Karl thrives on litigating matters where the legal terrain is uncharted, as is often the case in the realm of Internet disputes.

As a former general counsel to technology and non-technology companies alike, he has handled many of the day-to-day legal issues these companies face, including intellectual property issues, licensing and distribution agreements, and domain name disputes. Additionally, he handles a variety of transactions and business disputes for services, technology and media companies.


A former prosecutor and Army JAG Corps officer, he is both aggressive and creative in solving problems, while maintaining the highest of ethical standards.

Karl is frequently called upon as an Internet law expert by the media and at industry conferences. He has received the highest "AV Preeminent" rating by his peers through Martindale-Hubbell and is named to the 2011 list of Northern California Super Lawyers for his work in Internet law.

Karl is licensed to practice in California, New York, Georgia and Ohio and before the District Courts for the Northern, Central and Southern Districts of California, District Court for the Southern District of New York, District Court for the Northern District of Georgia, District Court for the Southern District of Ohio, and the United States Court of Appeals for the Ninth Circuit. He is a member of the American Bar Association and the Bar Association of San Francisco.

He is a graduate of the University of Notre Dame (1990) and the University of Cincinnati College of Law(1993).


Representative Matters


•Represented a major Internet advertising network in $11 million federal spam lawsuit by professional spam plaintiff. Prevailed on behalf of the client at summary judgment on all claims in the lawsuit. Obtained order awarding over $806,000 in fees and sanctions against the professional spam plaintiff, which pushed plaintiff into insolvency and caused them to cease operations.  


•Represented a cloud computing and file sharing company backed by more than $600 million in venture financing in a lawsuit where the firm successfully obtained the domain name containing the client’s primary trademark. 


•Represented a social networking app developer backed by more than $350 million in venture financing in a TCPA class action lawsuit.  Obtained speedy settlement and voluntary dismissal of putative TCPA class action against client, after early discovery and independent research by the Firm demonstrated that the SMS text message at issue was initiated by the plaintiff’s acquaintance, not the client.  


•Represented a medical records imaging technology company in lawsuit against an unknown person who hacked into client’s network. Upon discovering that the hacker was a competitor, and that the competitor stole trade secrets and used them to compete with client, the Firm amended the John Doe complaint to name the competitor as a defendant, leading to a complete win in the case and the criminal indictment of the defendant competitor.  


•Represented an international nonprofit organization in lawsuit involving theft of its trade secrets and dissemination of such trade secrets by defendants anonymously via multiple blogs.  


•Seized a domain name portfolio from a notorious cybersquatter and judgment debtor, auctioned the domain name portfolio for $302,000, and in the process created new Ninth Circuit law concerning the ability to seize domain names as property.  


•Represented defendants in an FTC lawsuit alleging $350 million in damages arising from what the FTC described as “bogus free trial offers”, including preparing and presenting nine expert witnesses in an opposition to a preliminary injunction.  


•Represented defendants in a FTC lawsuit involving $42.5 million regarding unsolicited SMS text messages marketing free gift cards, resulting in a public settlement where defendants paid only a fraction of the damages alleged by the FTC.  


•Represented a medical school in lawsuit against a bogus non-profit consumer review website and company; following a round of subpoenas served on various service providers for defendants, the firm discovered that the defendant was actually controlled by a direct competitor of the client.  The matter settled promptly after this revelation.   


•Represented the nation’s largest broker of moving and relocation services in false advertising lawsuit against a so-called consumer review website. The complaint alleged that defendant engaged in search engine spam by numerous uses of our client’s trademark under the auspices of a “black list”, which directly benefited the competitors of the firm’s client.  


•Represented the nation’s top retailer of ink and toner products in a false advertising lawsuit brought by a billion dollar printer manufacturer.  


•Represented the U.S. Chess Federation in a lawsuit involving unknown parties hacking into the email account of a member of the board of directors of our client, and stealing information regarding the internal investigation of two other directors of the organization (Susan Polgar and Paul Truong).  After multiple rounds of subpoenas, the firm discovered that the person responsible for the hacking was an employee of Susan Polgar, which led to the criminal indictment of such employee and an eventual resolution of the case.  


•Defeated motion for class certification in hotly-contested, multi-million dollar consumer class action against Internet advertiser by using arguments made by plaintiff in refusing to arbitrate—namely, that the version of the website plaintiff viewed did not contain certain disclosures—against him to demonstrate that plaintiff could not establish the requisite commonality or typicality.  The case was resolved shortly thereafter through voluntary dismissal by plaintiff and no payment by the client. 


Karl Stephen Kronenberger
150 Post Street, Suite 520
San Francisco, CA, 94108-4707


5.0 / 5.0
  1 customer review
5 Star
4 Star
3 Star
2 Star
1 Star
Posted by Dustin Mitchell | September 30, 2016
This review is from a potential client who consulted with this attorney.
| Consulted Attorney
Great representation
Consulted with his firm on several issues that were impacting my company Dustin


We have not found any cost information for this lawyer

Contact for Details


AVVO RATING 10.0 (Superb)

Work Experience

  • Partner
  • Kronenberger Rosenfeld, LLP
  • 2003 - Present
  • Prosecutor / Defense Attorney
  • U.S. Army JAG Corps
  • 1994 - 1998


  • University of Cincinnati College of Law
  • JD - Juris Doctor
  • 1993
  • University of Notre Dame
  • BA - Bachelor of Arts
  • 1990

Sample of Legal Cases

  • Hypertouch, Inc. v., Inc. et al., Case No. 09-15943 (9th Cir.)
  • Case dismissed, affirmed on appeal.
  • Office Depot and Assigniee DS Holdings v. Zuccarini,621 F.Supp.2d 773 (N.D. Cal. 2007), affirmed, 596 F.3d 696 (9th Cir. 2010).
  • The domains names were auctioned and the proceeds distributed to the judgment creditor.
  • ASIS Internet Services v., Inc., Case No. 08-15979 (9th Circuit)
  • Decision for defendant, affirmed on appeal.
View all legal cases


  • ABA Cyberspace Law Committee
  • Member
  • 2011 - Present
  • American Association for Justice
  • Member
  • 2008 - Present
  • Bar Association of San Francisco
  • Member
  • 2004 - Present
  • American Bar Association
  • Member
  • 2003 - Present
  • State Bar of California, Business Law Section, Cyberspace Committee
  • Co-Vice Chair, Co-Chair
  • 2012 - 2014
View all associations

Honors and Awards

  • AV Preeminent Peer Rating
  • Martindale-Hubbell
  • 2012
  • Northern California Super Lawyers
  • Super Lawyers
  • 2011
  • Inducted as Colonel
  • Honorable Order of Kentucky Colonels
  • 1997
  • Inducted
  • The Order of the Barristers
  • 1993
View all awards


  • Intellectual Property Magazine
  • Customer Lists "in the heads" of Ex-Employees
  • 2015
  • Inside the Minds: Understanding Developments in Cyberspace Law, 2014 ed.
  • The Tension Between Principles of “Sunshine Laws” and “The Right to be Forgotten” – Trends in the Treatment of Personal Information on the Internet
  • 2014
  • Daily Journal
  • Defamation Superhighway
  • 2009
  • Directions, IMA Newsletter
  • Fight Back Against Internet Defamation (a war story from a battle-hardened attorney)
  • 2009
View all publications

Speaking Engagements

  • Internet Law Leadership Summit
  • What is a Web3 Domain Name, and Why IP Practitioners Should Know About Them? (.eth, .crypto, .nft, etc.)
  • 2022
  • RV Industry Industry Association Conference
  • Defamation, Free Speech, and Reputation Management in the RV Industry
  • 2019
  • Internet Law Leadership Summit
  • Trends in Dealing with Unauthorized Sellers on Amazon
  • 2018
  • Intellectual Property Law Section of The State Bar of California
  • Unpacking Hassell v. Bird
  • 2017
  • Catalyst88
  • Legal Issues for Amazon Sellers
  • 2017
  • Internet Law Leadership Summit
  • Copyrightability Under the Copyright Act
  • 2016
  • The Intellectual Property and Internet Law Section of the Barristers Club
  • Online Marketing: Current Trends & Common Pitfalls
  • 2015
  • Internet Law Leadership Summit, May 2015
  • Employers' Use of Social Media – NLRB and Other Updates
  • 2015
  • Internet Law Leadership Summit
  • Employers' Use of Social Media – NLRB and Other Updates
  • 2015
  • Bar Association of San Francisco
  • Online Advertising Panel
  • 2015
  • Testimony Regarding AB 2643 Revenge Porn Civil Claim for Relief
  • Testimony at Hearing of Judiciary Committee of California Assembly
  • 2014
  • Internet Law Leadership Summit
  • Nonconsensual Content Distribution: New Laws, Judgments and Case Strategies.
  • 2014
  • State Bar of California, Business Law Section, Cyberspace Committee
  • New TCPA Requirements and Surging SMS Spam Litigation
  • 2013
  • State Bar of California, Business Law Section, Cyberspace Committee
  • Recent Developments in TCPA Compliance and Litigation Regarding SMS Spam
  • 2013
  • Internet Law Leadership Summit
  • Serving Subpoenas on ISPs, Email Providers and other Vendors: Pitfalls and Best Practices
  • 2013
  • Internet Law Leadership Summit
  • Spam Litigation Update
  • 2013
  • Internet Law Leadership Summit
  • SMS Spam Litigation Explosion
  • 2013
  • Internet Law Leadership Summit
  • Spam Law Thunderdome: A Vigorous Debate on Current Spam Law Developments
  • 2013
  • Internet Law Leadership Summit
  • Mobile Privacy & COPPA: Recent Updates and Impending Regulatory Changes
  • 2013
  • "Hot Topic" Presentation, Business Law Section of the State Bar of California
  • Mobile Privacy and SMS Marketing: Recent Updates and Impending Regulatory Changes
  • 2013
  • Internet Law Leadership Summit
  • SMS Spam Liability Under the TCPA and State Law: Compliance and Litigation Strategies
  • 2012
  • Cyberlaw Leadership Summit
  • Investigations and Pretexting: Legal and Ethical Considerations
  • 2012
  • ABA Winter Working Meeting and Cyberspace Law Institute
  • Waging War on Anonymous Bad Actors on the Internet
  • 2012
  • 3rd Annual Intellectual Property Law Symposium
  • Enforcing IP on the Internet: Ethical Issues and Investigative Tools in Pursuing Anonymous Infringers
  • 2012
  • Cyberlaw Leadership Summit
  • Legal Ethics of Online Marketing
  • 2011
  • Cyberlaw Leadership Summit
  • Technology Solutions in Cyberlaw
  • 2011
  • Email Marketing in 2008: What Every Company Should Know
  • Legal Compliance and Risk Minimization for Email Marketing
  • 2008
  • Countdown with Keith Olbermann
  • Internet Defamation
  • 2008
  • ABC News NOW
  • Net Neutrality
  • 2008
  • SEO & SEM Marketing Conference
  • Legal Compliance When Engaging in SEO and SEM Internet Marketing
  • 2007
View all speaking engagements

Attorney endorsements

Received (8)
Given (10)
Endorse Karl
Internet Attorney | Nov 28
Relationship: Worked together on matter
"I've worked with Karl on several matters, and have been thoroughly impressed. Karl is an experienced litigator, tactful negotiator, and achieved great results on our matters. I'm proud to know Karl."
Intellectual property Attorney | Jul 14
Relationship: Fellow lawyer in community
"I met Karl at a recent Internet Lawyer Conference. I recommend him as a person and an attorney."
Internet Attorney | Apr 03
Relationship: Worked together on matter
"I endorse this lawyer."
Unknown Attorney | Jul 29
Relationship: Opposing Counsel on matter
"Karl is among the best of the best. I have had the pleasure of working with him on many matters, and I have always found him to be well-prepared, creative and trustworthy. Perhaps most importantly, he is effective. Karl wins cases."
Internet Attorney | Jun 20
Relationship: Fellow lawyer in community
"I endorse and recommend Karl without hesitation. Over the last few years, I have come to know Karl, understand the manner in which he practices law and manages his firm, hear him speak on diverse legal issues, and, to my benefit, develop a collegial relationship with him. As to the manner in which he practices law, he is an attorney's attorney. He understands the law, appreciates the nuances of situations, advocates a strong position for his clients, and, this is important, he is respectful, professional and ethical. As to substantive knowledge, Karl is well-respected among peers throughout the country."
Internet Attorney | Dec 31
Relationship: Opposing Counsel on matter
"I have worked with and opposite Karl on a number of matters. He is a true professional and one of the best in the space. Extremely knowledgeable and many of his cases make new law."
Intellectual property Attorney | Jul 13
Relationship: Fellow lawyer in community
"Quite simply, Karl is an exceptional attorney. He is brilliant, savvy, hard working, creative, and honest. Unlike other lawyers who dabble in Internet and intellectual property law, Karl has extensive experience and really knows this area of the law."
Internet Attorney | Aug 07
Relationship: Worked together on matter
"Karl is a trusted colleague and well respected lawyer is a highly specialized field."
View more endorsements
Consumer protection
Intellectual property
Corporate and incorporation
Brain injury
Corporate and incorporation
San Francisco Internet Lawyer Karl Stephen Kronenberger
Karl Stephen Kronenberger
Internet Attorney
San Francisco, CA
Licensed for 30 years