Musselman Library has specialized databases for searching scholarship from many disciplines, but MUSCAT Plus can be a good place to begin because of its broad scope and interdisciplinary coverage.
You might want to identify think tanks that cover specific policy realms, but a trial search in Policy Commons is an excellent starting point because it checks publications from hundreds of think tanks, NGOs, and policy organizations at the same time.
HeinOnline searches thousands of law reviews as well as the entire Congressional Record, Federal Register, and Code of Federal Regulations. It's a great place to find legal scholars' interpretations of specific cases and pieces of legislation.
Zotero is citation-management software that exists to make your life easier. If you're interested in setting it up and seeing how it works, here is what you need to do: