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About me

For over 35 years, Mr. Lassen has concentrated his legal practice in the field of workers compensation, handling cases not only though the Illinois Workers Compensation Commission, but through the Circuit and Appellate Courts, as well.


Mr. Lassen began his legal career as an Assistant Attorney General, subsequently working 17 years as partner in the Chicago firm of Koutsky, Boudreau, Lassen and Mason.  He has maintained his own practice in Wheaton since 1998.


Mr. Lassen has presented seminars to various groups and has guest lectured at John Marshall School of Law.  He is currently a member of the Du Page County Bar Association and the Illinois Workers Compensation Lawyers Association.


In addition, Mr. Lassen is associated with experienced and highly awarded personal injury counsel devoted to handling personal injury and wrongful death cases arising from automobile accidents, train and plane crashes, product liability, medical malpractice and construction site accidents.


Photos and videos

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Practice areas


  1. Personal Injury: 50%
  2. Workers Compensation: 50%

Attorney endorsements

2 total 

Are you an attorney? Endorse this lawyer

  • Matthew C Simon

    Mr. Lassen provides insightful, helpful and accurate advice. His knowledge and experience are clearly evident. I endorse this lawyer.


    Matthew Simon Personal injury Attorney
    Relationship: Fellow lawyer in community

  • Christian K. Lassen II

    I endorse this lawyer.


    Christian Lassen Wrongful death Attorney
    Relationship: Fellow lawyer in community

Contact info

The Law Office of Brian D. Lassen

214 N Hale St
Wheaton, IL, 60187-5115


ILActive And Authorized To Practice Law198005/11/2016
We have not found any instances of professional misconduct for this lawyer.
Avvo contributions
Legal answers
Work experience
TitleCompany nameDuration
PartnerKoutsky, Boudreau, Lassen and Mason1981 - 1998
Association namePosition nameDuration
Workers’ Compensation Lawyers AssociationN/A1980 - Present
School nameMajorDegreeGraduated
Chicago-Kent College of Law Illinois Institute of TechnologyLawJD - Juris Doctor1980
Wheaton College, Wheaton ILEconomicsN/A1977