You will have no doubt heard about the accusations against Milan Kundera. One notes, just like every commentator who has no access to the documents and so is in absolutely no position to judge, that the accusations seem to be based on very little.
This is a good rejoinder (from euro|topics):
In the daily El País the Czech writer Monika Zgustova criticises the accusations levelled at her fellow countryman, the writer Milan Kundera, who, on the basis of secret service documents, is suspected of denouncing an anti-communist activist to the police in 1950.
"How can an accusation with such grave consequences be made on the basis of a single dubious document and use so many vague expressions? Dubious because in the Czechoslovakia of the 1950s it was routine for the police to receive denunciations, for every police official who received a denunciation could be sure of being awarded a medal ... Both the Czech and the international press were quick to comment on the article [in Respekt] and to spread the accusations against Kundera. In this way we became witnesses ... to something very grave: we were witness to massive accusations against a person in the midst of democracy, without the documents referred to even being questioned, without knowing whether there were any other documents, without hearing other witnesses and above all without listening to the accused's own version of the events."