After his studies of law at the universities of Mainz, Berlin, Munich and Kiel, Smidt joined the German Federal Intelligence Service in the 1960s in Pullach under their legendary founder Reinhard Gehlen.

He was one of the first high-ranking German government representatives who publicly denounced the alleged US American proofs for weapons of mass destruction in the Iraq as evident falsifications, easily recognizable as such by any professional secret service.

If one totally forgets about one's own core values, it is not worth it.“[10] His condemnation of secret actions of the CIA directed against Muslim individuals in Europe, which included illegal kidnappings, in 2005 received wide attention in the press.

[11] In 2011 he organized a conference on secret services and the question of ethics ("Ethik und Nachrichtendienste") at the Evangelische Akademie Bad Boll, with the participation of important representatives of the international intelligence community, from the USA, Russia, Israel, France among others.

He was involved in numerous book publications which focus on the question of the uneasy interconnection between democratic principles and secret services, among others together with the German government's Federal Agency for Civic Education (BPB)[12]