Tradition is one of the tenets upon which Campion, Curran, Dunlop & Lamb, P.C. is built. In 1851, Merritt Joslyn was admitted to the bar. When his son David followed him in his Woodstock practice in 1898, David was recognized as "one of the most capable, successful and resourceful attorneys who ever practiced in McHenry County." In 1914, Merritt's grandson, David R. Joslyn, Jr. joined the family in the practice of law. Later in his career, David formed a partnership known as Joslyn & Green, which in 1980 merged with the Firm of Welsh, Holmstrom, Gaines & Lindstedt to become Holmstrom & Green.

The forerunner of the Welsh, Holmstrom Firm also began practicing law before the turn of the century when R. K. Welsh, a trial lawyer who later became circuit judge in Rockford, was joined in practice by his three sons. John Holmstrom joined the Welsh Law Firm in 1948, and shortly thereafter Alex Welsh, R. K. Welsh's grandson, also became a member of the Firm. John F. Kennedy, who began practice in 1954, merged his Lake Forest office into Holmstrom & Green in 1983. In 1989, the Firm's name was changed to Holmstrom & Kennedy, P.C. In April of 1994 the Rockford and Crystal Lake offices were separated and the McHenry County Firm became Campion, Curran, Rausch, Gummerson & Dunlop, P.C., while the Rockford office name remained unchanged.

In 2004, the firm name changed to Campion, Curran, Dunlop & Lamb, when Mark Gummerson and Tom Rausch formed Gummerson & Rausch, LLC.