Defining the problem the policy is addressing will help shape your research.Understanding the background of an issue will help you make better informed decisions when you evaluate the information you find during your research.
Here are excellent sources and techniques to help you get started:
Searching the library catalog by subject: United States -- Social policy. Using that subject search provides you with a wide range of topics. Re-sort by "reverse year" to view the most recently published materials.
eBook Collections: Search these collections for authoritative works on your topic.
The Contemporary World Issues series is a great source for background information. Search the library catalog for the title of this series to see all of the topics covered.
Reference books (in print) to browse for key terms and leaders in the policy context:
Encyclopedia of Policy Studies Ref. H97 .E6 1994
International Encyclopedia of Public Policy & Administration Ref. H97 .I574 1998
Encyclopedia of Activism and Social Justice Ref. HM671 .E53 2007
Social Issues in America: An Encyclopedia Ref. HN57 .S624 2006
The mass media can be a great source for public opinion and debate surrounding a policy issue.