 As a member of the House of Delegates, he was Deputy Minority Whip from 1997–1998.In 1998, Stull and Brinkley easily won re-election defeating Democratic challenger Valerie M. Hertges

In 2002, Brinkley was elected to the Maryland Senate, representing District 4, which covers Carroll County and Frederick County.He defeated Republican incumbent Timothy R. Ferguson in the primary election.