As per recent news, South Africa has brought to the International Court of Justice (ICJ) a claim that Israel has genocidal intent in its 2023 war in Gaza:
South Africa seeks to prove that the measures Israel has taken go beyond self-defence and into the destruction of the Palestinians. The claim details the familiar, if shocking, death toll, forced displacement, deprivation of food, and the restrictions on births, through attacks on hospitals, saying they are sufficient evidence to infer plausible genocidal intent.
If any country were to take this legal motion, why was it specifically South Africa making this claim? What's the relation between South Africa and this war and the two parties involved? What are relevant causative and explanatory factors? Is there any possible hidden motive or underlying, non-obvious reason? Even if there is not, and it was arbitrary and by chance that South Africa made this claim, then why haven’t any other countries done this before them? What’s been stopping them?