The spread of horizontal relationships muddies that accountability. They replace hierarchical authority with networks sometimes formally constructed through contracts and other legal agreements, sometimes informally drawn through pragmatic working relationships (Kickert, Klijn,
and Koppernjan 1997; Milward and Provan 1998; Provan and Milward 1995; Nohira and Eccles 1992; Chisholm 1989).