Joseph Flahavan worked his way through Northwestern College of Law, graduated and was admitted to the bar on June 14, 1915. He then found a position in the credit department at Dayton's Department Store, and this in turn put him in contact with Art Rotering, who owned Commercial Services Company, a collection agency. Joseph Flahavan joined this company in 1920, bought it in 1941, and operated it until a month before his death in October 1953. In memorial services for the Hennepin County Bar Association the following year, he was recalled:
"Mr. Flahavan?s record as a lawyer is one to be proud of. While many of the individual cases which he handled involved comparatively small amounts, the volume of business which he conducted and the care and efficiency with which he did his work and built his organization resulted in his enjoying a very satisfying legal practice. Measured by the modern yardstick of income he was very successful in his highly specialized practice.
"Mr. Flahavan was a just and conscientious man. He was eminently fair, both in his dealings with his clients and with those against whom it was necessary for him to proceed. Never in his long history was he known to have been accused of sharp practices or mean and small dealings. On the contrary, Joe Flahavan many times took it upon himself, and at his own expense, to make it easier for debtors against whom it was necessary for him to proceed. He was always ready to grant a favor to a fellow lawyer but seldom, if ever, asked one for himself."