G. Marshall Hann began his legal career at the prestigious large downtown firm of Hillsinger & Constanzo. While at this firm, G. Marshall Hann was part of the named partner, John Constanzo's hand picked team that handled and defended large products liability and personal injury cases in Federal Court and other business related claims.

Since practicing in Santa Clarita Valley in 1984, G. Marshall Hann has tried cases in Federal Court, Bankruptcy Court, and State Courts, before both Judge and Juries.

Clients (past and present) include large corporations, single individuals, real estate developers and corporations (both large and small).