ICERD definition from 1965 was superseded in precision by the 1998 Rome Statute of the ICC. While ICERD utilizes a wide umbrella for "racial discrimination," the Rome Statute, which is the definitive modern authority on Crimes Against Humanity, specifically delineates 7 distinct categories of identity: political, racial, national, ethnic, cultural, religious, and gender.
Under accepted rules of statutory interpretation, the explicit separation of "ethnic," "national," and "religious" from "racial" in the Rome Statute means that, for the purposes of int'l criminal law, these categories are legally distinct and mutually exclusive. If "racial" were intended to include "ethnic" or "national" origin within the context of the Rome Statute, those 2 categories would be redundant, a conclusion that no serious int'l legal scholar or court would accept.
Therefore, the crime of Apartheid per Article 7 of Rome Statute is specifically and exclusively defined as an institutionalized regime of systematic oppression and domination by one "racial group" over another. Because Rome deliberately separates "ethnic" and "racial" into different classifications for other crimes against humanity (such as Persecution), one cannot retroactively use a 1965 definition to override the specific, tiered classifications of the 1998 Statute. To suggest that "racial" can simply be swapped for "ethnic" to satisfy the definition of apartheid is a legal maneuver that ignores the evolution of intll law and the strict construction required by the Rome Statute.