Los Angeles County Superior Court. Effective April 8, 2013, except as to those cases that may be filed in the North District (Antelope Valley Courthouse) pursuant to LASC Local Rule 2.3 (a)(1)(B), all Los Angeles Superior Court probate cases (all actions and proceedings to which the Probate Code applies) must be filed in Room 429 in the Stanley Mosk Courthouse, located at 111 N. Hill St., Los Angeles 90012.