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Karl Stephen Kronenberger


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About me

Karl Kronenberger is an indispensable resource and trusted advisor to his clients on issues relating to Internet law, media and technology.

A seasoned litigator, Karl has tried more than 20 jury trials and many more bench trials, and he regularly handles complex Internet 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. 


Practice areas


  1. Internet: 40%
    18 years
  2. Intellectual Property: 30%
    18 years
  3. Libel: 20%
    18 years
  4. Business: 10%
    18 years


Payment types:


Attorney endorsements

7 total 

Are you an attorney? Endorse this lawyer

  • Eric J. Menhart

    I met Karl at a recent Internet Lawyer Conference. I recommend him as a person and an attorney.


    Eric Menhart Litigation Attorney
    Relationship: Fellow lawyer in community

  • Ansel Jay Halliburton

    I endorse this lawyer.


    Ansel Halliburton Corporate and incorporation Attorney
    Relationship: Worked together on matter

Contact info


NYCurrently registered 200803/07/2016
GAActive Member in Good Standing 199807/15/2016
We have not found any instances of professional misconduct for this lawyer.
Avvo contributions
Legal answers
Award nameGrantorDate granted
AV Preeminent Peer RatingMartindale-Hubbell2012
Northern California Super LawyersSuper Lawyers2011
Inducted as ColonelHonorable Order of Kentucky Colonels1997
InductedThe Order of the Barristers1993
Work experience
TitleCompany nameDuration
PartnerKronenberger Rosenfeld, LLP2003 - Present
Prosecutor / Defense AttorneyU.S. Army JAG Corps1994 - 1998
Association namePosition nameDuration
State Bar of California, Business Law Section, Cyberspace CommitteeCo-Vice Chair2012 - Present
ABA Cyberspace Law CommitteeMember2011 - Present
American Association for JusticeMember2008 - Present
Bar Association of San FranciscoMember2004 - Present
American Bar AssociationMember2003 - Present
Legal cases
Case nameOutcome
St. Matthew's Univeristy School of Medicine v. Saba University School of Medicine, et. al.Settled
Estate of Anthony Quinn v. ZournasDomain Name Transferred
U.S. Chess Federation v. Susan Polgar, et al., CGC-08-476777 (3:08-CV-05126-MHP after removal to federal court).The civil case eventually settled.
See all legal cases 
Publication nameTitleDate
Intellectual Property MagazineCustomer Lists "in the heads" of Ex-Employees2015
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 Internet2014
Directions, IMA NewsletterFight Back Against Internet Defamation (a war story from a battle-hardened attorney)2009
Daily JournalDefamation Superhighway2009
School nameMajorDegreeGraduated
University of Cincinnati College of LawLawJD - Juris Doctor1993
University of Notre DamePhilosophy, Politics & EconomicsBA - Bachelor of Arts1990
Speaking engagements
Conference nameTitleDate
PLI's Sixteenth Annual Institute on Privacy and Data Security LawThe Last Year in Privacy and Security Litigation2015
Internet Law Leadership Summit, May 2015Employers' Use of Social Media – NLRB and Other Updates2015
Bar Association of San FranciscoOnline Marketing: Current Trends & Common PItfalls2015
Webmaster RadioKarl Kronenberger Discusses His $250,000 Revenge Porn Verdict2014
Testimony Regarding AB 2643 Revenge Porn Civil Claim for ReliefTestimony at Hearing of Judiciary Committee of California Assembly2014
Internet Law Leadership SummitNonconsensual Content Distribution: New Laws, Judgments and Case Strategies.2014
State Bar of California, Business Law Section, Cyberspace CommitteeNew TCPA Requirements and Surging SMS Spam Litigation2013
State Bar of California, Business Law Section, Cyberspace CommitteeRecent Developments in TCPA Compliance and Litigation Regarding SMS Spam2013
Internet Law Leadership SummitServing Subpoenas on ISPs, Email Providers and other Vendors: Pitfalls and Best Practices2013
Internet Law Leadership SummitSpam Litigation Update2013
Internet Law Leadership SummitSMS Spam Litigation Explosion2013
Internet Law Leadership SummitSpam Law Thunderdome: A Vigorous Debate on Current Spam Law Developments2013
Internet Law Leadership SummitMobile Privacy & COPPA: Recent Updates and Impending Regulatory Changes2013
"Hot Topic" Presentation, Business Law Section of the State Bar of CaliforniaMobile Privacy and SMS Marketing: Recent Updates and Impending Regulatory Changes2013
Internet Law Leadership SummitSMS Spam Liability Under the TCPA and State Law: Compliance and Litigation Strategies2012
Cyberlaw Leadership SummitInvestigations and Pretexting: Legal and Ethical Considerations2012
ABA Winter Working Meeting and Cyberspace Law InstituteWaging War on Anonymous Bad Actors on the Internet2012
3rd Annual Intellectual Property Law SymposiumEnforcing IP on the Internet: Ethical Issues and Investigative Tools in Pursuing Anonymous Infringers2012
Cyberlaw Leadership SummitLegal Ethics of Online Marketing2011
Cyberlaw Leadership SummitTechnology Solutions in Cyberlaw2011
Software Licensing Agreements - American Conference InstituteEliminating Ambiguity and Minimizing Risk with Warranty, Limitations of Liability, and Indemnification Provisions2009
Email Marketing in 2008: What Every Company Should KnowLegal Compliance and Risk Minimization for Email Marketing2008
Countdown with Keith OlbermannInternet Defamation2008
ABC News NOWNet Neutrality2008
SEO & SEM Marketing ConferenceLegal Compliance When Engaging in SEO and SEM Internet Marketing2007

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