There are several types of legal structure which these organisations by which AOTUs may be governed Traditionally, urban public transport was organised by the French communes, especially in the south of France.
Since the 1970s, however, AOTs have tended to combine across communes, with the creation of numerous syndicats intercommunaux à vocation unique (SIVUs; inter-commune single-purpose syndicates) with a remit only for the direction of urban transport.
In 2004, some years after the adoption of the 1999 loi relative au renforcement et à la simplification de la coopération intercommunale (law for the improvement and simplification of inter-communal cooperation), usually known as the loi Chevènement, the most common structure for AOTUs were as communautés d’agglomération (agglomeration communities), at 43% of the total, with communautés de communes (communities of communes) making up 12% and communautés urbaines (urban communities) making up 5% of all AOTUs.
Additionally, mixed syndicates represented 12% of the total in 2004, when SIVUs (8%) and syndicats intercommunaux à vocation multiples (SIVOMs; inter-commune multi-purpose syndicates) (1%) were being phased out.
Contractual relations between the AOTU and the contractor can also take many different forms: for example as a délégation de service public or a droit des marchés publics en France.