A Federal case is a criminal case that falls under the jurisdiction of a federal court.
Federal courts are established under the U.S. Constitution to decide disputes involving the Constitution and laws passed by Congress. Federal courts only hear cases in which the United States is a party, cases involving violations of the U.S. Constitution or federal laws (under federal-question jurisdiction), cases between citizens of different states if the amount in controversy exceeds $75,000 (under diversity jurisdiction), and bankruptcy, copyright, patent, and maritime law cases.
Federal cases are a primary source.
State cases involve individual citizens and issues such as, robberies, traffic violations, broken contracts, and family disputes. These cases are tried in state courts, which have a broad jurisdiction. The only cases state courts are not allowed to hear are lawsuits against the United States and those involving certain specific federal laws: criminal, antitrust, bankruptcy, patent, copyright, and some maritime cases.
State and local courts are established by a state (within states there are also local courts that are established by cities, counties, and other municipalities, which we are including in the general discussion of state courts).
State cases are a primary source.
Law reviews are scholarly publications, usually edited by law students in conjunction with faculty members. They contain both lengthy articles and shorter essays by professors and lawyers, as well as comments, notes, or developments in the law written by students. Law review articles often focus on new or emerging areas of law. Many times, they can offer more critical commentary than a legal encyclopedia or ALR (American Law Report) entry. Some law reviews are dedicated to a particular topic, such as gender and the law or environmental law, and will include in their contents the proceedings of a wide range of panels and symposia on timely legal issues.
Law reviews are a secondary source. They are valuable for the depth in which they analyze and critique legal topics, as well as their extensive references to other sources, including primary sources.
Courtesy of Harvard Law School Library: https://guides.library.harvard.edu/c.php?g=309942&p=2070278