When I was growing up and I would complain to my mother that I wanted to do something that she would not allow or that my sister had done something to me, my mother often would respond: “Don’t make a federal case out of it.” Well, little did my mother know that I would spend a great deal of time as an adult doing just that.

The phrase “make a federal case out of it” is defined by the Merriam-Webster Dictionary as an informal idiom that means “to become very upset or angry about (something that is not important).” One of the highest compliments I ever have received as a lawyer was when I sued a local government in federal court on behalf of a client who had been denied the ability to sell pizza in a government-owned market and the government’s counsel telephoned me and screamed, “I never thought I would see the day when a lawyer could make a federal case out of a slice of pizza.” Sometimes selling a slice of pizza is important, but making a federal case out of one often is not easy.

There are two parallel court systems in the United States: state courts and federal courts. State courts are courts of general jurisdiction. Federal courts are courts of limited jurisdiction. Most cases are filed in state court and remain there. Many cases only can be filed in state court, but some can only be filed in federal court.

There are two broad classes of cases that can be filed in federal court: (1) those arising under the Constitution, laws, or treaties of the United States; and (2) those between citizens of different states or between citizens of a state and citizens or subjects of a foreign state. Although these classes sound simple, they sometimes are not. For example a United States citizen who is domiciled outside of the United States is not a citizen of a state and, thus, cannot supply the necessary “diversity of citizenship” for the second category of cases. Also, a case in the second category must involve a dispute the value of which exceeds $75,000.

The types of cases that fall into the first class have expanded as Congress has created new federal causes of action. For example, in 2016 Congress enacted the Defend Trade Secrets Act that allows the owner of a trade secret to sue in federal court when its trade secrets have been misappropriated. But not every case involving a federal law claim will remain in federal court. A notable example involved claims under the federal Racketeer Influenced and Corrupt Organizations Act (“RICO”) against the directors and officers of Old Court Savings & Loan, the collapse of which sparked the Maryland savings and loan crisis of the late 1980s. The Supreme Court of the United States affirmed a lower federal court’s holding that the case more appropriately belonged in state court because of Maryland’s comprehensive scheme for rehabilitation and liquidation of insolvent state-chartered savings and loan associations.

Usually the plaintiff decides where a case will be filed. However, in certain circumstances, a defendant may remove a case from state court to federal court. There are pros and cons to litigating in each system depending upon the nature of the case and the circumstances of the particular state and federal court in which a case can be litigated. For example, some federal courts are incredibly backlogged and one can get to trial faster in state court. But, the reverse also is true. The jury pools in federal court usually are broader and have citizens from throughout the state in which the federal court sits whereas state court jury pools usually include only citizens from the county in which the state court sits.

The interaction between state and federal courts is something in which I have been interested since I was in law school. I now teach a course on federal court jurisdiction at the University of Baltimore School of Law. I always am ready to talk about where a case can be filed and if it can be filed in state or federal court, which court system is the best one for that particular case. Insofar as how to make a federal case out of a slice of pizza goes, that is a trade secret.