The lowest court level in Texas is the Justice of the Peace Court (also called Justice Court or JP Court). Sections 18 and 19 of Article V, as well as Chapters 27 and 28 of the Texas Government Code, outline the duties of these Courts and their officers.

Under Section 18, the number of JP's (and associated constables) is dependent on the size of the county:

For counties with populations less than 18,000 (as determined by the census), the entire county shall be one JP precinct, unless the Commissioners' Court determines that more are needed, in which case the court can divide the county into no more than four JP precincts.

For counties with populations at least 18,000 but less than 50,000, the number of JP precincts shall be no less than two nor more than eight.
For counties with populations 50,000 or greater, the number of JP precincts shall be no less than four nor more than eight.

In any county with population less than 150,000, if any precinct contains a city with 18,000 or more population, that precinct shall have two JP's.
In any county with population 150,000 or greater, each JP precinct may have more than one JP.

Special provisions apply to Chambers and Randall counties (must have no fewer than two nor more than six precincts) and to Mills, Reagan, and Roberts (the Constable office is abolished, with the Sheriff's office performing all duties).
Section 19 sets forth the minimum jurisdiction of the JP court:

Original jurisdiction in "criminal matters of misdemeanor cases punishable by fine only" (called "Class C" misdemeanor cases under the Texas Penal Code),
Exclusive jurisidction in "civil matters where the amount in controversy is $200 or less", and "Such other jurisdiction as may be provided by law". Under this provision, the Legislature has raised the top limit on civil matters to $10,000 and assigned the JP courts, among others, the right to hear cases involving eviction as well as cases involving foreclosure and liens against personal property where the amount falls within the (revised) JP Court's jurisdiction.
In addition, the JP is an ex-officio notary public.

There is no requirement that the JP be an attorney. However, the Texas Government Code requires a JP to attend an 80-hour course involving the performance of JP duties within one year after initial election, and a 20-hour course every year thereafter.

JP cases are appealed to the county court level where the case results in a trial de novo. In criminal cases, cases beginning in justice court cannot be appealed beyond the county level court unless the the fine is more than $100 or a constitutional matter is asserted.