One of the main purposes of Terwagne's law is to associate the regions to the economic planning. Three regions: Flanders, Wallonia and Brabant are instituted and endowed with organs, the SDR (regional development society) and the CBR (regional economic council). The CERB (regional economic council for Brabant) took part to the regionalisation of the Plans. But various factors made this regionalisation insufficient. The CERB still expressed views on the used water purification, transport infrastructure, territory planning and institutional matters. Moreover, the ERB greatly developed its research mission rather than claiming activity. Meanwhile, the subsequent development of the ideas about regionalisation led to a delimitation of a central region not the same as that instituted by the economic decentralisation: the Brussels region restricted to nineteen communes. The activity of CERB makes it primarily a consultative organ of the future regional institutions. But as a preliminary, the geographical competence of the CERB and its composition must be modificated. To organize a real regionalisation, it is necessary to suppress technical impediments (deficiency in delays and information) and it is also necessary that the consultation should be complete and real.