The son of Ingvar Hjermann, Reidar started working as a psychologist in 1998. In 2004 he was appointed Ombudsman for Children in Norway, succeeding fellow psychologist Trond Waage.[1]
When his four-year term ended in 2008, he applied for a second term. However, the job was given to jurist Ida Hjort Kraby. Later, it was revealed that Kraby had friendly relations with Minister of Children and Equality, Manuela Ramin-Osmundsen. Ramin-Osmundsen withdrew from her position, as did Kraby, who never got the time to formally enter the post. With the ombudsman position open again, Hjermann was then appointed to a second term, where he served until the end of the term in 2012.[1]