He served first for the Public Against Violence (VPN) party from 26 September 1990 until 12 November 1991.

[3][4] In 1995 he criticized the government of Slovak Prime Minister Vladimír Mečiar, saying the state was becoming more and more authoritarian.

[1] In April 2014, during the crisis in Ukraine he disagreed with Slovak government policy on defence of Slovakia.

He called for increased security efforts, including the possibility of stationing NATO troops in the country.

[8] Šebej is member of the board of the Slovak Foreign Policy Association.