He was politically active as a student, serving as chair of Den Konservative Studenterforening, Det Norske Studentersamfund, and the construction committee for Chateau Neuf.

[1] His initial professional experience was as an attorney and manager for the deep sea shipping company Wilh.

Jan P. Syse met Else Walstad (1936–2021)[1] while they both were students at the University of Oslo in 1955,[citation needed] and they were married in 1959.

He was also sent as a parliamentary delegate to the United Nations General Assembly, Nordic Council, Inter-Parliamentary Union, and other international bodies.

Syse was State Secretary to the Ministry of Justice from 1 November 1970 to 17 March 1971 in the non-Socialist coalition government led by Per Borten.