The Texas Constitution states that "[t]here shall be established in each county in this State a County Court ..." Sections 15 through 17 of Article V, as well as Chapters 25 and 26 of the Texas Government Code, outline the duties of these Courts and their officers.

Section 15 states that the County Court shall be a "court of record", and states that the county judge shall be "well informed in the law of the State", "a conservator of the peace", and shall be elected for a four-year term. Section 16 states that the County Court "has jurisdiction as provided by law"; Section 17 states that the County Court shall hold terms as provided by law and that County Court juries shall consist of six persons, but in civil cases a jury shall not be empaneled unless one of the parties demands it and pays a jury fee or files an affidavit stating that it is unable to do so.

The county court has appellate jurisdiction over JP and municipal court cases (for municipal court cases, this may involve a trial de novo if the lower court is not a "court of record"), exclusive jurisdiction over "Class A" and "Class B" misdemeanors (these offenses can involve jail time), and concurrent jurisdiction over civil cases where the amount in controversy is moderately sized.

Since the county judge is also responsible for presiding over the Commissioners Court (the main executive and legislative body of the county), in most counties the Texas Legislature has established county courts at law to relieve the county judge of judicial duties. In most counties with courts at law, the civil and criminal jurisdiction of the constitutional county court has been transferred to the county courts at law. The county courts at law may hear both civil and criminal matters, or hear them separately, depending on how the Legislature has structured them. Unlike the county judge, judges of the county courts of law are required to be attorneys.

In another unique twist, the Constitution grants the Legislature the authority to determine which court handles probate matters. Thus, in ten of the 15 largest counties (specifically, the counties of Bexar, Collin, Dallas, Denton, El Paso, Galveston, Harris, Hidalgo, Tarrant, and Travis) the Legislature has established one or more Statutory Probate Courts. These specialized courts handle matters of probate, guardianship, trust, and mental health. In some counties, the statutory probate courts also hear condemnation cases. There are no jurisdictional monetary limits on the types of lawsuits that a statutory probate court may hear. As such, their jurisdiction at times overlaps that of the district court.