Hacker, Jacob S. and Paul Pierson. 2010. “Winner-Take-All Politics: Public Policy, Political Organization, and the Precipitous Rise of Top Incomes in the United States.” Politics & Society 38: 152-204.
In which Hacker and Pierson show that US inequality is all about gains to the top at the expense of everyone else; and they show how this was accomplished through government policy.
Specifically, they introduce the concept of policy drift. Policy drift occurs when a) changes in the market or society render existing policy incapable of achieving its substantive goals, and b) organized interests (eg. politicized capital) successfully lobby against updating policy, thereby rendering policy counterproductive or ineffective.
The abstract is here at Politics & Society.