This included their obligation to settle disputes peacefully, Australian judge Hilary Charlesworth said.
"I think many countries regard international law as a somewhat distant system of law that doesn't really affect them and regularly put national priorities before the priority of fully implementing their international legal obligations," she told AAP.
"All members of the United Nations, for example, have a duty imposed by the Charter of the United Nations to resolve disputes by peaceful means and clearly that basic principle of international law is often ignored."
The comments do not reflect on any particular conflict or nation, the international court judge made clear because any inferences could interfere with what cases she would be able to preside over.
"As an international lawyer, I unsurprisingly would wish that countries would take their international legal commitments more seriously," she said.
But the comments come during a precarious time in geopolitics where China's transgressions in the Indo-Pacific, Russia's invasion of Ukraine and Israel's war against Hamas in Gaza have put a renewed focus on international law and order.
The international court settles disputes between nations and gives advisory opinions on legal questions referred to it by the UN.
It's preparing advisory opinions on the legal consequences arising from Israel's policies in the occupied Palestinian territory, including East Jerusalem and on states' obligations concerning climate change following a push from Vanuatu.
It is also presiding over allegations from Ukraine that Russia erroneously used the genocide convention to justify its invasion.
The court's findings on disputes are final and binding for the parties who have consented to its jurisdiction. There is no option for appeal.
Judge Charlesworth was re-elected to the court in November.
Australians were able to bring a broader perspective than their Western counterparts with the country being situated in the Asia-Pacific, she said.
"Because we're based in the Pacific, I think Australians bring a keen appreciation of our region and understanding," she said.
"We're an island nation and we have very close relations with Pacific neighbours and I think that's a really valuable perspective."
