▁became ▁known ▁collect ively ▁as ▁the ▁" Europe an ▁Commun ities ", ▁for ▁example ▁the ▁Commission ▁was ▁known ▁as ▁the ▁" Comm ission ▁of ▁the ▁European ▁Commun ities ", ▁although ▁the ▁communities ▁themselves ▁remained ▁separate ▁in ▁legal ▁terms . ▁ ▁Struct ural ▁evolution ▁of ▁the ▁European ▁Commission ▁ ▁P ill ar ▁ ▁The ▁Ma astr icht ▁Tre aty ▁built ▁upon ▁the ▁Single ▁European ▁Act ▁and ▁the ▁So lem n ▁Dec laration ▁on ▁European ▁Union ▁in ▁the ▁creation ▁of ▁the ▁European ▁Union . ▁The ▁treat y ▁was ▁signed ▁on ▁ 7 ▁February ▁ 1 9 9 2 ▁and ▁came ▁into ▁force ▁on ▁ 1 ▁November ▁ 1 9 9 3 . ▁The ▁Union ▁su pers eded ▁and ▁absor bed ▁the ▁European ▁Commun ities ▁as ▁one ▁of ▁its ▁three ▁pill ars . ▁The ▁first ▁Commission ▁President ▁following ▁the ▁creation ▁of ▁the ▁EU ▁was ▁Jacques ▁Del ors , ▁who ▁briefly ▁continued ▁his ▁previous ▁E EC ▁ten ure ▁before ▁hand ing ▁over ▁to ▁Jacques ▁San ter ▁in ▁ 1 9 9 4 . ▁ ▁Only ▁the ▁first ▁pill ar ▁followed ▁the ▁principles ▁of ▁su pr an ational ism . ▁The ▁pill ar ▁structure ▁of ▁the ▁EU ▁allowed ▁the ▁areas ▁of ▁European ▁co - operation ▁to ▁be ▁increased ▁without ▁leaders ▁hand ing ▁a ▁large ▁amount ▁of ▁power ▁to ▁su pr an ational ▁institutions . ▁The ▁pill ar ▁system ▁seg reg ated ▁the ▁EU . ▁What ▁were ▁formerly ▁the ▁compet encies ▁of ▁the ▁E EC ▁fell ▁within ▁the ▁European ▁Community ▁pill ar . ▁Justice ▁and ▁Home ▁Affairs ▁was ▁introduced