In parliament, he was made a frontbench spokesman on Health in 1997 by Paddy Ashdown. Following the election of Charles Kennedy as party leader in 1999, Harris became spokesman on Higher Education and Women's issues. He was promoted to the Liberal Democrat shadow cabinet following the 2001 general election as Shadow Secretary of State for Health, but stood down in 2003 to care for his girlfriend Liz O'Hara who had been diagnosed with terminal glioblastoma multiforme. Following the 2005 general election, Harris returned to the frontbench team as spokesman on Science, a position he held until his defeat in the 2010 general election.