A party official and well-known technocrat, Černík was a strong supporter of the Prague Spring reforms of 1968. In August 1968 he was forced to go to the Soviet Union along with other politicians, and when he returned he asked the Czech people to cooperate with the Soviet Union but promised to continue reforms. In 1970 he lost his position due to his continued support of reform and was expelled from the communist party. He attempted a political comeback in the early 1990s after the end of the communist regime. He died in Prague.