Illegalism is an anarchist philosophy that developed primarily in France, Italy, Belgium, and Switzerland during the early 1900s as an outgrowth of individualist anarchism. The illegalists openly embraced criminality as a lifestyle.
Illegalism first rose to prominence among a generation of Europeans inspired by the unrest of the 1890s, during which Ravachol, Émile Henry, Auguste Vaillant, and Caserio committed daring crimes in the name of anarchism, in what is known as propaganda of the deed.
Influenced by theorist Max Stirner's egoism, the illegalists in France broke from anarchists like Clément Duval and Marius Jacob who justified theft with a theory of la reprise individuelle (Eng: individual reclamation). Instead, the illegalists argued that their actions required no moral basis - illegal acts were taken not in the name of a higher ideal, but in pursuit of one's own desires. "In Paris, this milieu was centred on the weekly paper, L’Anarchie and the Causeries Populaires (regular discussion groups meeting in several different locations in and around the capital each week), both of which were founded by Albert Libertad and his associates".
After Peter Kropotkin along with others decided to enter labor unions after their initial reservations, there remained "the anti-syndicalist anarchist-communists, who in France were grouped around Sebastien Faure’s Le Libertaire. From 1905 onwards, the Russian counterparts of these anti-syndicalist anarchist-communists become partisans of economic terrorism and illegal ‘expropriations’." Illegalism as a practice emerged and within it "The acts of the anarchist bombers and assassins ("propaganda by the deed") and the anarchist burglars ("individual reappropriation") expressed their desperation and their personal, violent rejection of an intolerable society. Moreover, they were clearly meant to be exemplary, invitations to revolt.". But in another less dramatic sense "At that time this term was used to indicate all those practices prohibited by law that were useful for resolving the economic problems of comrades: robbery, theft, smuggling, counterfeiting money and so on."