Sean Grimsley

Litigation: General Commercial (Colorado)

Sean is a founding partner of Olson Grimsley Kawanabe Hinchcliff & Murray LLC, an impact litigation firm in Denver, Colorado that opened its doors in September 2023. Before founding Olson Grimsley, Sean spent 17 years as a trial lawyer and partner at Bartlit Beck. He has been an Assistant Federal Public Defender in Washington, D.C., Deputy Chief Counsel to President Obama’s Commission investigating the BP oil spill, Special Assistant Attorney General for the State of Colorado in its pattern and practice investigation of the Aurora Police and Fire Departments, and most recently General Counsel for two years at Ibotta, a billion-dollar tech company in Denver. Sean clerked for U.S. Supreme Court Justice Sandra Day O’Connor and Chief Judge Harry T. Edwards of the D.C. Circuit.

Fellow in the American College of Trial Lawyers;

Fellow in Litigation Counsel of America;

Colorado Lawyers Committee

Sean is one of the nation’s leading trial lawyers, trying four cases to judgment in Olson Grimsley’s first year alone. He was lead counsel in the country’s first trial against a preterm infant formula manufacturer for causing necrotizing enterocolitis where he and his team secured a $60 million compensatory damages verdict against Mead Johnson, the maker of Enfamil. He co-led a trial team that won a $20+ million judgment against Johns Manville, a Berkshire Hathaway company, for unlawfully monopolizing the market for calcium silicate pipe insulation. He co-led the trial team challenging Donald Trump's eligibility to appear on the 2024 presidential ballot in Colorado. And he co-led a trial team in Cook County, Illinois, against two makers of Zantac—GSK and Boehringer Ingelheim—for causing his client’s prostate cancer, ultimately settling on confidential terms with GSK and trying the case against Boehringer Ingelheim to a hung jury. It was the first trial against a Zantac manufacturer that did not end in a defense verdict.

In his last years at Bartlit Beck, Sean led the team that secured dismissal of the Grenfell Tower fire victims’ products liability mass action against Arconic in Philadelphia, tried a nine figure arbitration for a major energy company plaintiff, tried an eight-week antitrust jury trial in S.D.N.Y. for defendant Sabre resulting in a $5 million verdict on US Airways’ $1+ billion claim, and readied for trial a major plaintiff-side patent case that settled favorably shortly before trial.

Michigan Law School

J.D.

University of Texas at Austin

B.A.s in Liberal Arts (Plan II) and Biology