SAUNDERS, Cheryl <br/><br/>
Collaborative federalism 

 - Oxford :  Blackwell Publishers Limited,  June 2002 
<br/><br/> Famously, federalism combines self-rule with shared rule or unity with diversity. Typically, the mix is achieved by creating or preserving two levels of government, each with a direct relationship with the people, and by dividing power between them. Traditionally, unity is achieved through the exercise of power by the central government, in relation to the polity as whole. Diversity is the consequence of the exercise of power by sub-national governments over a portion of the population, generally territorially identified. The boundaries of power between the two spheres are secured by entrenching them in a written Cconstitution established as fundamental law, which is interpreted and applied by a court of courts