Sean O'Callaghan
O'Mara Gleason O'Callaghan
Litigation and Transactional Work

Sean O’Callaghan started his legal career as a misdemeanor trial assistant in the Cook County State’s Attorney’s Office in the Fourth Municipal District’s Maybrook Courthouse. There, on average, he saw 200 to 300 cases on each morning and afternoon court call.

It’s a courthouse in which young attorneys can easily become flustered.

But that never happened to O’Callaghan. Judge Paula Daleo of the Circuit Court of Cook County’s Fourth Municipal District said that hectic pace never rattled O’Callaghan.

“Achievement in this fast-paced environment is measured in preparedness and professionalism,” Daleo said. “Sean was the epitome of both. I have had many, many attorneys practice before me in my time as a judge, and Sean stands out among those many attorneys. Even in those early years when he was new to a courtroom, the chaos of it never seemed to rattle him, and he carried himself with the composure of a seasoned attorney.”

This young attorney rose through the ranks of the State’s Attorney’s Office and, after spending time in the Felony Trial Division, Sean left in 2013 and opened his own law practice, Chicago’s O’Mara, Gleason, O’Callaghan. There Sean uses the skills he learned as a State’s Attorney to take on a wide variety of civil litigation and transactional work. But no matter the case, O’Callaghan’s peers say he always gives his clients the best possible shot of earning a favorable result.

“Sean has demonstrated the ability to analyze legal issues in order to make sound and reasoned legal judgments,” said Joseph Hodal with the Cook County State’s Attorney’s Office. “Sean has always exhibited honesty, integrity, patience, tact and enthusiastic passion for any project or case that he dedicates his time to.”

Since his career change, O’Callaghan has achieved several noteworthy civil victories. This isn’t surprising since as a criminal attorney O’Callaghan successfully litigated hundreds of trials, hearings and motions.

In March of 2014, O’Callaghan was retained by a proprietary trading firm to investigate one of the firm’s directors who was believed to be embezzling. O’Callaghan, relying on his former experiences working with law enforcement, conducted an on-site investigation where he identified critical pieces of evidence which lead to the location of many stolen assets. He even interviewed the embezzler himself and obtained a signed confession.

Most impressively? All of this was done within 24 hours of being retained. Ultimately, he and his firm recovered nearly $450,000 in stolen funds and real estate for his client.

O’Callaghan’s path has been uniquely carved transitioning from prosecuting criminals to civil practice, but that path has proven results. O’Callaghan and his firm won a multi-million-dollar judgement in an employment litigation matter against a company represented by one of Chicago’s top-five law firms. He has litigated against one of New York City’s top firms in a dispute concerning a highly specialized area of futures markets and regulatory law. He also single handedly closed a multi-million-dollar transaction where the other side was represented by attorneys from a national law firm ranked in the AmLaw 200.

“His reputation among my colleagues in Maywood was that he was 100 percent reliable, always prepared, tenacious and that he knew how to put on a case, get his evidence admitted and respect the other side in the process,” said Judge Robert Senechalle with the Circuit Court of Cook County’s Law Division. “I think the exceptional result that Sean achieved was to behave every day as a prosecutor to the highest standards of a trial lawyer.”