About Yonaton M. Rosenzweig

When a company is facing a substantial liability or extensive harm to its business, Yonaton Rosenzweig protects and enforces their legal rights. Experienced in every stage of litigation, Yoni lays the groundwork for success in court or a favorable settlement. In trial or arbitration, Yoni knows how to advocate and achieve success for his clients — he has served as lead attorney on numerous cases where he secured wins with 9- and 10-figure dollar amounts at stake.

A thoughtful advocate for his clients

Yoni is a litigator and trial attorney representing clients in antitrust, unfair competition, intellectual property and general commercial disputes. From the earliest stages of litigation, Yoni seeks to understand the contours of the case so he can pursue the strongest aspect of the client's case and strategically apply pressure and develop facts. He has led every stage of litigation from investigation through summary judgment, trial and appeal. His clients are drawn from a variety of industries, including private equity, technology, real estate, software and entertainment.

For example, Yoni defended a major software provider of billing solutions against a $900 million claim for unlawful monopolization, prevailing before trial. Yoni also prevailed at trial as the lead attorney in defense of a private equity firm accused of wrongfully enforcing its contract rights and interfering with a $250 million development project. In addition to his work in state and federal court, Yoni also has significant experience trying cases in arbitration.

Prior to joining Katten's litigation team, Yoni practiced at Quinn Emanuel, where he was an integral team member on one of the biggest computer memory antitrust cases in the country, from complaint to trial. He also second-chaired the successful civil prosecution of large-scale intellectual property infringement and unlawful importation of printer ink cartridges.

⇣   Expand to read more

Practice Focus

  • Antitrust and unfair competition
  • Intellectual property including trade secrets, patents and copyrights
  • Business disputes and commercial litigation
  • Private equity
  • Arbitration
  • Fiduciary litigation

Representative Experience

  • Represented major software system provider defending against claims of predatory pricing. Obtained dismissal of nine-figure antitrust claim.
  • Defended private equity firm against $80 million damages claim for unfair competition. Obtained full defense verdict at trial as first chair and an award of attorney's fees.
  • Trial team member from complaint until trial in a six-week antitrust trial concerning the monopolization of the market for DRAM chips. *
  • Represented reseller of insurance products as antitrust plaintiff against major life insurance company that tried to eliminate the resale market, successfully establishing the existence of a single brand market.
  • Represented charter aircraft company in antitrust dispute with competitor.
  • Represented sell-side financial research firm in defense of claims of unfair competition and trade secret theft.
  • Represented ink cartridge manufacturer as plaintiff before International Trade Commission seeking to enjoin the importation of infringing goods, and then to enforce injunction for sanctions. *
  • Represented individual accused of idea and trade secret theft by former employee. Obtained full dismissal.
  • As appellate counsel, vacated injunction against $29 million foreclosure. Subsequently obtained complete defense judgment in trial court on summary judgment motion and award of attorney's fees.
  • Represented national bank against $10 million claim for interference with prospective economic advantage. Obtained defense judgment and award of attorneys' fees.
  • Represent international film distributors in obtaining affirmative summary judgment of more than $6 million from large Los Angeles production company due to its failure to achieve a screen release in the United States.
  • Multi-district litigation representing several hedge funds in lawsuits arising from failed investments; obtained $30 million settlement before trial as well as dismissal of $75 million in damages claims.
  • Lead nationwide litigation counsel for consumer legal services firm in business litigation stemming from the Federal Trade Commission’s shutdown of its practice.
* Experience prior to Katten