It began in 1892, when William J. Sandoz (1870-1929) started his law practice in Opelousas over a century ago. The son of Swiss immigrants, William J. received his law degree at Columbian University (now George Washington University) in Washington D.C. Upon returning to Louisiana, he began practicing commercial law in Opelousas. His practice included commercial-collection accounts, retail-collection accounts, and creditor and debtor rights in bankruptcy. He also was a Louisiana State Senator, a member of the Louisiana Constitutional Convention of 1921, and served as President of the St. Landry Homestead Association. He further founded the "Knights of Columbus" in Opelousas, LA, and served as a Referee (Judge) in Bankruptcy.

Lawrence B. Sandoz Sr. (1897-1945) joined his father (William J.) upon graduating from LSU Law School in 1919. This father-and-son team continued the commercial practice of law and handled many claims over various collection lists, as well as serving as counsel for many Louisiana-based financial institutions. Lawrence Sr. also served as City Attorney of Opelousas, LA.

William C. "Billy" Sandoz (1928-2004) - a third-generation Sandoz attorney - graduated from LSU Law School in 1950, where he was a member of the LSU Law Review, Phi Delta Phi Legal Fraternity, and Order of the Coif. Billy followed in the footsteps of his grandfather and father by continuing the commercial law practice. He expanded the firm by receiving claims from creditors all over America against debtors throughout Louisiana. In doing so, Billy opened additional offices, enlarged the staff, and instituted a state-of-the-art computerized collection system. Billy also represented debtors as a Bankruptcy attorney, and served 25 years as the standing Chapter 7 Bankruptcy Trustee for the Western District of Louisiana. Billy further testified in front of Congress regarding the reform of bankruptcy laws, and served as an adviser to Congress for The Bankruptcy Reform Act of 1978. For his efforts, Billy was named on page 166 of the 1983 book, "The Best Lawyers in America," was listed in "Who's Who in American Law," and was inducted into the LSU Law Center's Hall of Fame in 1987.

W. Simmons "Sim" Sandoz - the fourth-generation family attorney - who upon graduating from Loyola University Law School of New Orleans in 1977, joined his father (Billy) as partner at Sandoz Law Office. Sim was an instructor at LSUE and taught the bankruptcy paralegal course at USL (now University of Louisiana at Lafayette). He, like his father, also served as a Chapter 7 Bankruptcy Trustee in the Western District for 20 years. Sim is currently serving as President of the Southwest Louisiana Bankruptcy Bar Association. Further, as senior partner at Sandoz Law Office, Sim continues the commercial law practice, representing both creditors and debtors throughout the state of Louisiana.

Jeffrey Simmons Sandoz graduated cum laude from Western Michigan University's Cooley Law School in 2010. He is the 5th-generation Sandoz attorney, and is currently the junior partner at the firm, practicing collection law and bankruptcy with his father, Sim. Jeffrey also teaches the Business Law course at South Louisiana Community College.