Born in Besançon on 23 July 1928, Piaget joined LIP in 1946 and unionized with the French Confederation of Christian Workers (CFTC) on his first day.

[2] In 1964, he, alongside other members of the CFTC, founded the French Democratic Confederation of Labour (CFDT).

[citation needed] In 1973, when LIP filed for bankruptcy and threatened the closure of the Besançon factory, Piaget led a strike of CFDT union members.

At the end of the conflict, he declared "The success (of a trade union movement) is no longer needing a leader… or at least: their voice only counts as one".

Piaget retired in 1988, but maintained his activism within the Agir ensemble contre le chômage [fr] (AC !).