A member of the Christian Democratic People's Party (CVP/PDC), she headed the Federal Department of Justice and Police.

Educated at the University of Fribourg, Metzler served as the cantonal executive in charge of finance in Appenzell Innerrhoden from 1996 to 1999.

She was elected to the Swiss Federal Council on 11 March 1999, as a member of the Christian Democratic People's Party.

Metzler kept her seat until the end of the year and Christoph Blocher succeeded her on 1 January 2004.

She taught between February and July 2004 at the University of St. Gallen a class called "Gestaltungsmöglichkeiten in der Politik" which can be translated as "scope for design in politics".