Some of the sources you might want to use when analyzing public policy include newspaper articles, scholarly journal articles, oversight or implementation hearings, reports by think tanks or research centers, or government reports.
HELPFUL TIP: Try searching for Congressional Hearings post-enactment of your public law. These hearings, sometimes called "oversight" hearings provide Congress with information regarding implementation, problems and solutions. Use Congressional Publications: Select only Hearings from the facets on the left and enter the title of your law or keywords in the search box; adjust the dates covered range as well. Search example: (oversight or implementation) AND "energy policy act of 2005"
A sampling...
(A more complete list is here.) See the Getting the Article page of this guide for more info on searching for scholarly journal articles.