Texas Courts Online is a tremendously helpful online resource describing the relationships of all courts in Texas, from muncipal courts through the Texas Court of Criminal Appears. The site includes a chart showing the court heirarchy, ranges of authority and paths for appealing court decisions. It has a very helpful legal FAQ on matters related to judges, attorneys and defendants. .
District courts have original jurisdiction in all felony criminal cases, plus civil matters. In the more densely populated counties individual courts often specialize in criminal, civil, juvenile or family law. This web site includes a link to help find the district courts for each county in Texas.
Each Texas county has a single county court presided over by a county judge. The county courts have original jurisdiction over all Class A and Class B misdemeanor criminal cases. Unless otherwise established by county law, these courts have appellate jurisdiction in cases appealed from justice of the peace and municipal courts. In counties with large populations, statutory county courts assist the county court in their judicial functions, as established by state law.
Justice of the Peace Courts have original jurisdiction in Class C misdemeanor criminal cases. A justice of the peace has the authority to issue search warrants and arrest warrants. A Justice of the Peace can also be the coroner in counties with no medical examiner.