His father was then arrested in a Communist Party purge and sentenced to 25 years in prison in a show trial in the 1950s.

When the movement was crushed by the Soviet occupation of Czechoslovakia, Kavan emigrated to the United Kingdom, the country of his birth, where he was a member of the Labour Party from 1972 to 1990.

Before returning to former Czechoslovakia after the fall of the Communist government, Kavan spent 20 years in exile in the UK.

In 1991, back in Czechoslovakia, Kavan was wrongly accused of collaboration with the Czechoslovak secret service (StB) in the years 1969–1970.

He received several honorary degrees, including Honorary Fellow of the London School of Economics, Honorary Professor of Human Rights, Adelphi University of New York, and a number of human rights awards including Companion of Honour (UK), International Order of Merit (UK), and Presidential Roll of Honor (USA).