The lawyer said it was “painful” when he heard about how the Trump administration had separated more than 2,000 children from their families after they had crossed the US-Mexico border.
Mr Ferencz had been just 27 when he served as the chief prosecutor at the Einsatzgruppen trial, during which 22 Nazi officials were found guilty of killing more than a million people.
Mostly fleeing drug-related gang violence and poverty in Central American countries, they crossed the border illegally but often seeking asylum in the US.
The parents have been charged with a crime though US law requires asylum seekers to enter the country before applying for the protected status.
The administration separated the children because they are unable to enter the US criminal justice system and placed them in detention centres.
It was part of Attorney General Jeff Sessions’ “zero tolerance” policy”, which has not actually ended despite Mr Trump signing an executive order ending family separation.
“I knew the Statue of Liberty. I came under the Statue of Liberty as an immigrant,” Mr Ferencz said during the interview, which was posted on the UN website. His family came to the US from Romania when he was a child.
Referencing a line from the Emma Lazarus poem inscribed at the base of the statue – “I lift my lamp beside the golden door!” – Mr Ferencz said “the lamp went out when [Trump] said no immigrants allowed unless they meet the rules that we laid down”.
“We list crimes against humanity in the Statute of the International Criminal Court. We have ‘other inhumane acts designed to cause great suffering’. What could cause more great suffering than what they did in the name of immigration law? It’s ridiculous,” the prosecutor of war criminals said regarding the family separation policy.
Mr Ferencz’s comment comes after Mr Hussein – a Jordanian prince, former ambassador, and UN political officer during the Bosnian war – announced he would not seek another term as the world body’s top human rights official.
He had become known for taking a stand against Mr Trump in particular, calling the US leader “grossly irresponsible” when he implemented the Muslim travel ban.
In December 2017, Mr Hussein said in a letter to staff the summer of 2018 would be his last at the UN, stating: “After reflection, I have decided not to seek a second four-year term. To do so, in the current geopolitical context, might involve bending a knee in supplication; muting a statement of advocacy; lessening the independence and integrity of my voice — which is your voice.”
“There are many months ahead of us: months of struggle, perhaps, and even grief — because although the past year has been arduous for us, it has been appalling for many of the people we serve,” he wrote.