Federal crimes are criminal offenses based on legislation (laws or statutes) enacted by the United States Congress and published in the United States Code (U.S.C.). Most crimes (murder, rape, assault, burglary, etc.) are prosecuted under state law (statutes) and are known as state law crimes. In contrast, crimes prosecuted under federal law are known as federal crimes.

Federal crimes generally involve a subject over which the United States Constitution gives the federal government—and more specifically, the U.S. Congress—the power or authority to legislate or make laws. This power or authority is also known as jurisdiction.

For example, the federal government (and not the states ) has the exclusive authority to print money and regulate its value. And because bank deposits are guaranteed (insured) by the federal government (FDIC) up to $250,000 per depositor, per FDIC-insured bank, and per ownership category, bank robbery is a federal crime (18 U.S.C. §2113). Examples of other federal crimes include tax evasion, wire fraud, mail fraud, immigration offenses, voting or electoral fraud, counterfeiting money, espionage (spying), and damaging or destroying mailboxes.

In Alabama, as in all states, federal crimes are offenses that fall under the jurisdiction of the federal government, as established by the United States Constitution and legislated by the U.S. Congress. These crimes are distinct from state crimes, which are prosecuted under state law, and are codified in the United States Code (U.S.C.). Federal crimes typically involve matters that are within the exclusive domain of the federal government, such as counterfeiting currency, bank robbery due to the federal insurance of bank deposits by the FDIC, tax evasion, and immigration offenses. Federal agencies, such as the FBI, DEA, and ATF, are typically involved in the investigation and enforcement of federal laws. When a person in Alabama is charged with a federal crime, they are prosecuted in a federal district court, and the case is handled by attorneys from the U.S. Attorney's Office, rather than state prosecutors.