Cusack, Gilfillan & O'Day, LLC (CGO) was founded by Peoria attorney Dan Cusack on April 1, 1984. Joe Gilfillan and Dan O'Day joined the firm several years later and became partners in 1991.
As of 2012, the attorneys of Cusack, Gilfillan & O'Day, LLC have a total of over 75 years of experience practicing law in Central Illinois and have represented thousands of clients. The firm, consisting of nine attorneys, operates a general practice of law with each partner and associate concentrating in specific areas of practice. Cusack, Gilfillan & O'Day, LLC advises and represents both individuals and businesses with an emphasis on personal injury, workers' compensation, family law, real estate, civil litigation, criminal law, appeals, estate planning, probate, businesses, and employment litigation.