German judge Christian Tomuschat is facing increased pressure to step down as head of the UN panel charged with reviewing the implementation of the Goldstone report's demands.
Critics say Mr Tomuschat has already likened Israel's self-defence actions to "state terrorism", and thus cannot provide an unbiased assessment of whether Israel and Hamas have properly investigated and then tried those alleged to have committed war crimes during Operation Cast Lead.
Mr Tomuschat, professor emeritus at Humboldt University, Berlin, was named this summer as head of the panel, which is to submit its report in October. The other members of the committee are attorney and special UN rapporteur Param Cumaraswamy of Malaysia and former New York State Supreme Court Justice Mary McGowan Davis.
At issue are Mr Tomuschat's past statements on the Israeli-Palestinian conflict. In a 2002 essay on responses to terrorism, he wrote - commenting on Israel's military response to terrorist attacks - that a state that orders retaliation against "presumed terrorists" knowing civilians might be killed "deserve[s] the same blame as those targeted by them".
He also expressed doubt that such a state's judicial system could "conduct effective investigations and punish the responsible agents".
Speaking to the Jerusalem Post last weekend, Mr Tomuschat insisted that his past statements have been objective and ridiculed the suggestion that he resign from the panel.
But Hillel Neuer, director of the Geneva-based NGO, UNWatch, said that he should indeed step down.
"A panel tasked with assessing the effectiveness of Israel's war crimes investigations, headed by someone who has already made up his mind and declared himself on this precise question - against Israel - is not only absurd but a travesty of justice."
The appointment of an open critic of Israel is further evidence, he said, of an anti-Israel bias on the UN Human Rights Council, which includes as members states that are dictatorships, are implicated in genocide or otherwise have shady records on human rights.
"Even if it were Mother Therea and Mahatma Ghandi on the committee, the entire process would be tainted by bias," Mr Neuer said.
Recently the former foreign minister of Iceland, Ingibjorg Solrun Gisladottir, was removed from the UNHRC committee of inquiry into Israel's conduct in the ill-fated flotilla raid in May, after she was found to have signed a petition supporting the flotilla.
In his 2002 essay, Mr Tomaschut also suggested that the victim of a terror attack might be to blame for his own suffering: "Any state under terrorist attack should "analyse its own conduct and ask itself whether it has made mistakes which have given rise to frustration, hatred and despair."