Section 18Republic Act No. 296, otherwise known as the Judiciary Act of 1948, as amended, of Republic Act No. 9as amended, of the Rules of Court, and of all other statutes, letters of instructions and general o, Sec./Art. 18

Authority to define territory appurtenant to each branch. The Supreme Court shall define the territory over which a branch of the Regional Trial Court shall exercise its authority. The territory thus defined shall be deemed to be the territorial area of the branch concerned for purposes of determining the venue of all suits, proceedings or actions, whether civil or criminal, as well as determining the Metropolitan Trial Courts, Municipal Trial Courts, and Municipal Circuit Trial Courts over the said branch may exercise appellate jurisdiction. The power herein granted shall be exercised with a view to making the courts readily accessible to the people of the different parts of the region and making the attendance of litigants and witnesses as inexpensive as possible.