Following graduation from law school in 1967, Roger became associated with Don Herrling in a partnership that spanned over three decades. The partnership began as a general practice law firm. Over the years, the growth of the firm allowed for the development of more specialized practices.

Roger Clark developed specialties in personal injury litigation, municipal law, and municipal litigation. His advocacy lead to the development of one of the firm's major specialties: personal injury litigation. The municipal litigation earned him a statewide reputation in the field. The firm continues to consult with municipal clients on a statewide basis. He has also had appointments as an Instructor at the University of Wisconsin Law School in the Municipal Law course.

Roger was vice-president of the law firm from its inception. Upon Don Herrling's retirement as president, Roger held that position until 1997. In that year, Roger assumed an "of counsel" status with the firm. In that capacity, he has been working on projects and cases, and assists in the areas of his specialties. He has also offered his services as a mediator assisting in alternative dispute resolution. Roger continues to work with area towns and villages, and recently completed the legal framework for a new concept in multi-jurisdictional storm management.