A number of deniers have been prosecuted under various countries' denial laws. French literature professor Robert Faurisson, for example, was convicted and punished under the Gayssot Act in 1990. Some historians oppose such laws, among them Pierre Vidal-Naquet, an outspoken critic of Faurisson, on the grounds that denial legislation imposes "historical truth as legal truth". Other academics favor criminalization. Holocaust denial, they contend, is "the worst form of racism and its most respectable version because it pretends to be a research".