Until now, the trade and environment interdependence in multi-level-governance settings has been mostly addressed through a transfer of old concepts, bound to a central nation state, onto other levels of governance, framing the trade and environment debate as a solely horizontal issue. These approaches missed the potential vertical aspect of trade and environment conflicts in multi-level-governance settings. The thesis of this paper is that a comparative analysis of federal-type legal structures and how they address the trade and environment issue can enhance the trade and environment debate and help to find feasible solutions for diagonal conflicts in multi-level-governance settings. For this analysis the paper chooses a largely neglected field of liberalization, the EU, U.S. and WTO procurement regime.