Political Science Complete Search
Start with a search for the general topic in a periodical database like Political Science Complete
Older, more mature topics will be covered in books, emerging topics will only be in periodicals.
Legislative histories can give you the root issues that were being addressed by a piece of legislation, law review pieces will tell you how the courts have interpreted the law in specific circumstances. See the CQ Almanac, CQ Researcher or Congressional Research Service reports for background on issues. (ex) ADAA 2008
For detailed case history see LexisNexis Federal Cases and law review pieces