The Council of Europe Explanatory Report of the protocol states "European Court of Human Rights has made it clear that the denial or revision of "clearly established historical facts – such as the Holocaust – [...] would be removed from the protection of Article 10 by Article 17" of the ECHR (see in this context the Lehideux and Isorni judgment of 23 September 1998)".
The Council of Europe's Explanatory Report on the protocol clarifies that the European Court of Human Rights has stated that denying or altering "clearly established historical facts, such as the Holocaust," would be excluded from Article 10 protections by Article 17 of the ECHR. This is supported by the Lehideux and Isorni judgment issued on September 23, 1998.