Berth was the national chairman of Danish People's Party's Youth from 1999 to 2007, and a member of the Danish People's Party central board from 1999 until 2013. He was a member of the Capital Region of Denmark region council from 2010 to 2015. Since 2010 he has been a member of the municipal council of Vallensbæk Municipality.[3][1]
Berth has been a substitute member of the Folketing twice, substituting for Søren Espersen. First time was from 22 February to 6 March 2011, and the second time was from 22 October to 7 November 2014. At the 2015 Danish general election he was elected as a member of the Folketing from the Greater Copenhagen constituency.[1]
In 2016, Berth had some criticism when he suggested shooting at boats carrying migrants.[4][5][6]
Berth has written books about the history of the Danish People's Party's Youth, about the Progress Party and its founder, Mogens Glistrup, and about criticism of the Danish public school curriculum.[1]
Bibliography
En dansk fremtid – historien om Dansk Folkepartis Ungdom 1995-2005 (2005)
Skolen i løgnen – løgnen i skolen – hvordan skolebøger hetzer og indoktrinerer (2006)
Fremskridtspartiet under Glistrup – Mogens Glistrup og Fremskridtspartiet 1972-1984 (2008).