Liebler & St. Hilaire, P.S. is the oldest law firm in Kennewick, continuously operating since 1909. Attorneys Mark M. Moulton and Scott Z. Henderson opened a law firm in downtown Kennewick on November 1, 1909. Mark Moulton continued to practice law with the firm until his retirement in 1957. At that time, the firm name continued on with the remaining partners, Powell & Loney until 1959, when Charles L. Powell was appointed to the bench for the US District Court. Dean Loney continued with the firm until 1978. Craig Liebier joined the firm in 1976, and his name was added in 1979, and remains on to honor his forty (40) years with the firm, second only to firm founder Mark Moulton. Following is the history of firm names from 1909 to present.
| Moulton & Henderson | 1909-1913 |
| Moulton & Jeffrey | 1913-1921 |
| Moulton Law Office | 1922-1931 |
| Moulton & Powell | 1931-1951 |
| Moulton, Powell, Gess & Loney | 1951-1955 |
| Moulton, Powell & Loney | 1955-1957 |
| Powell & Loney | 1957-1959 |
| Loney, Westland & Koontz | 1959-1964 |
| Loney, Westland, Koontz & Raekes | 1964-1970 |
| Loney, Westland & Raekes | 1970-1971 |
| Loney, Westland, Raekes & Rettig | 1971-1973 |
| Loney, Westland, Raekes, Rettig & Sonderman | 1973-1976 |
| Loney, Westland, Raekes, Rettig, Sonderman & Osborne | 1976-1977 |
| Loney, Westland & Sonderman | 1978 |
| Westland, Sonderman & Egan | 1978-1979 |
| Westland, Sonderman, Egan, Liebler & Ivey | 1979-1981 |
| Westland, Liebler & Ivey | 1981-1989 |
| Liebler, Ivey, Larsen, Quigley & Hugill | 1989-1991 |
| Liebler, Ivey, Larsen & Quigley | 1991-1994 |
| Liebler, Ivey & Connor | 1994-2003 |
| Liebler, Ivey, Connor & Berry | 2003-2004 |
| Liebler, Ivey, Connor, Berry & St. Hilaire | 2004-2007 |
| Liebler, Connor, Berry & St. Hilaire | 2007-2018 |
| Liebler & St. Hilaire, P.S. | 2018-present |
