Primarily the U.S. District Courts, though there are other trial courts as well, including magistrate courts, the bankruptcy courts, the U.S. Court of International Trade, the U.S. Court of Federal Claims, various military courts, and the U.S. Tax Court.
For a detailed summary of the U.S. federal court system, see "Understanding Federal and State Courts" at <http://www.uscourts.gov/EducationalResources/FederalCourtBasics/CourtStructure/UnderstandingFederalAndStateCourts.aspx>
Federal courts may hear civil cases or criminal cases.
Federal courts of general jurisdiction (US District Courts, etc.) handle both civil and criminal cases.
United States district courts consider criminal and civil cases that come under federal authority.
The United States has a "dual court system" consisting of state courts that primarily hear civil and criminal cases related to state laws and state constitutional issues, and federal courts that primarily hear civil and criminal cases related to Federal Laws, US treaties and the US Constitution.
Federal district courts have trial jurisdiction over most cases in the federal system.
Courts that have the authority to be the first courts in which most federal cases are heard are known as district courts. These are the trial courts of the federal judiciary system and are responsible for hearing both civil and criminal cases.
they have original jurisdiction over most federal cases
Charging and trying defendants for breaking federal laws.
Criminal cases and civil cases
. . . . ANY violations of federal laws and regulations, both civil and criminal, including the tax codes.
The u.s. District Courts are the trial courts of all Federal Court Systems. Both civil and criminal cases are filed here.
The dual court system refers to the separate Federal and State court systems in the United States. Federal courts hear criminal and civil cases that involve constitutional and federal law, policies and special subject matter (such as Bankruptcy, or Federal Tax). State courts hear civil and criminal cases related to state laws and state constitutional issues.