Born in 1957, Pierre de Preux obtained a degree in law at the University of Geneva in 1979 and was called to the bar in the same year. From 1984 to 1998 he worked as a partner in the firm Cramer & de Preux, then, once Robert Cramer was elected to the State Council, he joined the firm de Pfyffer in which he was partner until 2006, after which he found the firm de Preux + associés and joined, in June 1st, 2012, the firm Canonica Valticos de Preux + associés.
Pierre de Preux mainly carries on a judicial activity in business criminal law, in counsel and litigation in commercial and banking matters as well as in media law.
He was the First Secretary of the Young Bar Association from 1988 to 1990, member of the Bar Association Council from 1998 to 2004, President of the Geneva Bar Association from 2000 to 2002, and chaired the criminal law Commission, then the Human rights Bar Commission from 2002 to 2008. He took over the secretariat of the Dakar Resolution of the international Conference of Bar Association of common judicial tradition regarding the death penalty abolition. From 1990 to 1996, he was deputy Judge at the Jurisdiction Court, then, from 2004 on, deputy Judge at the Court of Cassation.
He served on the Bar Committee Supervisory Authority from 2006 to 2014, which he chaired since 2010. He was then a member of the Supervisory Council of the Judges from 2017 to 2020.
Substitute lecturer at the lawyer School of the University of Geneva, he conducted a seminar of professional practice dedicated to criminal hearings.