Kokkinakis v. Greece, No. 14307/88, ECtHR (Chamber), 25 May 1993

The criminal conviction of a Jehovah’s Witness who has engaged in acts of proselytism constitutes a breach of Article 9 ECHR.

Art. 9 ECHR

1. Freedom of religion is one of the foundations of a democratic society within the meaning of the Convention. It is, in its religious dimension, one of the most vital elements that go to make up the identity of believers and their conception of life, but it is also a precious asset for atheists, agnostics, sceptics and the unconcerned. The pluralism indissociable from a democratic society, which has been dearly won over the centuries, depends on it.

2. While religious freedom is primarily a matter of individual conscience, it also implies, inter alia, freedom to "manifest one’s religion". Bearing witness in words and deeds is bound up with the existence of religious convictions. According to Article 9 ECHR, freedom to manifest one’s religion includes in principle the right to try to convince one’s neighbour, for example through "teaching", failing which, moreover, "freedom to change [one’s] religion or belief" would be likely to remain a dead letter.
(The case revolves around the criminal conviction imposed, in Greece, on a Jehovah's Witness who had engaged in conversations on religious matters with his neighbor, the wife of an Orthodox cantor. The sanction is not considered by the Court to be necessary in a democratic society)

The judgment is a leading case in matter of right to freedom of religion. For the first time, a link is recognized between this freedom and the identity of all the individuals (believers, atheists, agnostics, sceptics and unconcerned). It is a leading case in matter of religious proselytism as well.