As a result of the enormous suffering inflicted upon the world by the Nazi regime, and especially Europe, a number of European countries have enacted laws criminalizing both the denial of the Holocaust and the promotion of Nazi ideology.
The aim of these laws is to prevent the resurrection of Nazism in Europe by stamping out at the earliest opportunity any public reemergence of Nazi views, whether through speech, symbols, or public association. …
… such laws and their strict enforcement is necessary to prevent the reemergence of Nazism, which, in a repeat of the events in pre-war Germany, is particularly attractive to individuals living in countries where unemployment and social dissatisfaction is high.
The anti-Nazi laws do not exist in every European country. Presently, the following European countries have some legislation criminalizing the Nazi message, including denial of the Holocaust: Austria, Belgium, the Czech Republic, France, Germany, Liechtenstein, Lithuania, the Netherlands, Poland, Romania, Slovakia, Spain and Switzerland. Holocaust denial is also illegal in Israel. …
A last set of countries put a higher value on free speech over suppression of neo-Nazism and freely allow promotion of the Nazi message. In these countries, freedom of the press and freedom of speech are vehemently upheld even to the detriment of other rights. These countries include the United Kingdom, Ireland and the Scandinavian nations.
Holocaust Denial Laws and Other Legislation Criminalizing Promotion of Nazism
by Michael J. Bazyler
http://www1.yadvashem.org/yv/en/holocaust/insights/pdf/bazyler.pdf