 A helpful categorisation among federal arrangements concerns the relationship between the central unit, member units and individuals. If the decisions made centrally do not involve member units at all, we may speak of separate (split or compact) federalism. Some issues may be the responsibility of the central unit, others belonging to the member units, where citizens vote their representatives directly to both bodies (U.S. Constitution Art. II Section 1; cf. Dahl 2001). Federations can involve member units in central decision-making in at least two different ways in various forms of interlocking (or cooperative) federalism. Member unit representatives can participate within central bodies—in cabinets or legislatures—(collective agency compositional arrangement). Or they constitute one central body that interacts with other central bodies, for instance where member unit government representatives form an Upper House with power to veto or postpone decisions by majority or qualified majority vote (divided agency/relational arrangements). These legal arrangements give rise to varieties of multi-level governance: continuous negotiations among authorities at different territorial levels (Marks 1993, Hooghe and Marks 2003, Scharpf 1983). Responsiveness to individuals may benefit from interlocking federalism, but often at the cost of transparency and accountability.