 His first marriage lasted from 1957 to 1981, the second to deputy under-secretary of state Kirsten Ullbæk Petersen (born 1950) started in 1984.He was a research fellow from 1959 and docent from 1964, and took the dr.juris degree in 1968 on the thesis "Det såkalte husbondsansvar".From 1968 to 2001 he was a professor at the University of Oslo, and he also served as dean of the Faculty of Law from 1989 to 1994.