Thanks for your response. An apartheid regime can even be found absent the presence of laws designed to restrict the rights of groups of people. This example by Human Rights Watch has a fairly simply (and I think effective) definition that is effective, and law-based: https://www.hrw.org/news/2021/07/19/israeli-apartheid-threshold-crossed#:~:text=International criminal law%2C including the,by one racial group to

International criminal law, including the 1973 International Convention on the Suppression and Punishment of the Crime of Apartheid and the 1998 Rome Statute to the International Criminal Court, define apartheid as a crime against humanity consisting of three primary elements: (1) an intent by one racial group to dominate another; (2) systematic oppression by the dominant group over the marginalized group; and (3) particularly grave abuses known as inhumane acts.