I've come across the idea of a null morpheme. There are languages with determiners that are case particles. Since a morpheme can be a particle, I would assume there might be languages with null determiners that are case particles.
Is there a language with such a property, where all noun phrases have case particles, one of which is interpreted as a null case particle and is part of its case paradigm (similar to a morphological case declension table)?
The language in question can have case particles that are either post-positions or pre-positions, and of course the number of cases in the case paradigm can be any number above 2.
EDIT: The zero particle or particle dropping in Colloquial Japanese doesn't qualify since it has stylistic/pragmatic usage.
EDIT2: The null case particle must mean only one case relation (nominative, accusative, dative, genitive, etc.), and must participate in a case paradigm, where it must contrast with other overt/non-null case particles that signal different case relations. The presence or absence of the null case particle changes the case relation of the NP, and not just for differential subject/object marking.