About Us
Simonsen Sussman is an antitrust law firm founded by former federal enforcers who together have decades of experience with federal and state antitrust and unfair competition laws through government investigations and in private and public litigation across the country.
Our mission is to help those harmed by anticompetitive and unfair practices. We bring timely, efficient, and high-impact competition actions which are critical to opening up markets to new entry, making our economy more dynamic, and enabling a fair distribution of the benefits of competition to all.
Meet Our Team
Catherine Simonsen
Catherine is a Partner and Co-Founder of the firm. She brings over a decade of experience investigating and litigating complex antitrust cases on both the plaintiff and defense sides in federal and California state courts.
Shaoul Sussman
Shaoul is a Partner and Co-Founder of the firm and a seasoned antitrust practitioner with extensive experience in private and government practice.
Kate Brubacher
Kate is a Partner and Co-Founder of the firm and a seasoned practitioner at the highest levels of private and federal practice. Prior to co-founding the firm, Kate was the United States Attorney for the District of Kansas.
Nicolas Stebinger
Nicolas, a Partner and Co-Founder of the firm, is a seasoned trial lawyer and antitrust practitioner. Nicolas has investigated, prosecuted, and defended a broad array of antitrust lawsuits.