He gained notoriety in 1982 with the book Suicide, mode d'emploi [fr], which sold over 100,000 copies before being banned.
His parents were dental surgeons in the public sector and his grandfather, also named Claude [fr], was a deputy of the National Assembly from 1928 to 1932.
In 1977, he became a freelance objector for Libération and was an activist within the "sexual revolution" within the French movement for family planning [fr].
On 28 August 1996, he was the victim of police violence during a demonstration against the expulsion of undocumented immigrants from Saint-Bernard de la Chapelle.
[2] The year after Guillon's book was published, the Senate adopted a bill against "incitement to suicide", which was passed by the National Assembly in 1987.