What seals the case against Israel is the statements of high ranking Israelis all the way up to Netanyahu. And what seals the case against Israel’s allies is their fulsome support for what Israel’s doing. From Jonathan Cook at unz.com:

Israel’s allies aren’t just turning a blind eye to Gaza’s killing fields. They have cheered on the bloodshed, provided diplomatic cover and supplied the arms
Israel is urging western states to rally to its side as the International Court of Justice prepares to hear this week South Africa’s case that Israel is committing genocide in Gaza.
The court is being asked by Pretoria to issue an immediate injunction ordering Israel to halt its military assault on the tiny enclave, to avoid further casualties.
Some 23,000 Palestinians are known to have been killed by Israel so far, a majority of them women and children, and many thousands more are believed to be lying under the rubble. Tens of thousands are seriously wounded. A majority of the population have lost their homes to the three-month bombing campaign.
Israel has intensively and repeatedly targeted the supposedly “safe zones” to which it has ordered Palestinian civilians to flee.
It has destroyed almost all of Gaza’s infrastructure and is blocking most aid from reaching the enclave. Famine and disease are likely to rapidly increase the death toll.
South Africa’s 84-page brief argues that Israel’s bombing campaign and siege breaches the 1948 Genocide Convention, which defines genocide as “acts committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group”.
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