Carlile was created a life peer on 27 July 1999, as Baron Carlile of Berriew, "of Berriew in the County of Powys", having previously been a Liberal Democrat Member of Parliament for Montgomeryshire from 1983 to 1997; he had stood unsuccessfully as a Liberal for East Flintshire in February and October 1974. As the sole Welsh Liberal Democrat MP for Wales after the 1992 election, Carlile helped steer the party through one of its low points. He was instrumental in the pre-devolution discussions with the Welsh Labour Party that led up to the 1997 devolution referendum.