During inflectional expansion, if there are cases marking subject, object, and attribute, there are also local and other adverbial cases. During inflectional reduction, if there are local and other adverbial cases, there are also subject, object, and attributive cases.
Standardized
During inflectional expansion, IF there are cases marking subject, object, and attribute, THEN there are also local and other adverbial cases. During inflectional reduction, IF there are local and other adverbial cases, THEN there are also subject, object, and attributive cases.
Ancient and Modern Greek (both Greek), French, Italian, Latin (all Italic), English, “Gothic” (both Germanic), Classical Armenian (Armenian), Hebrew (Semitic, Afro-Asiatic)
Is actually not a developmental law, but a universal implication, holding only for (all) languages in a particular stage of their evolution.