Federal Lands Hazardous Fuels Reduction Act of 2003 - Authorizes the Secretary of Agriculture and the Secretary of the Interior to conduct hazardous fuels reduction projects on National Forest System lands, and Bureau of Land Management lands, respectively. Provides for: (1) a collaborative project selection process; and (2) an expedited planning and implementation process.Directs the Secretaries to jointly contract with the National Academy of Sciences to define old and large trees.Sunsets provisions of this Act five years after its enactment.Waives temporarily certain transfer limitations on use of the Reforestation Trust Fund.