The International Criminal Court has ordered its prosecutor to reconsider laying charges against Israel for a 2010 raid on a flotilla carrying aid to Gaza that killed 10 Turkish citizens.
"The prosecutor is directed to reconsider her decision by December 2, 2019,” presiding appeals judge Solomy Balungi Bossa told the court on Monday.
The Mavi Marmara was among eight ships trying to break Israel's naval blockade of Gaza on May 31, 2010, when it was boarded by Israeli marines in international waters.
They killed nine Turkish men and another died four years later in hospital.
A 2010 UN Human Rights Council report found that the Israelis used "an unacceptable level of brutality" and broke international laws in the operation.
After the killings, relations between Turkey and Israel fell apart but were mended in secret talks years later.
Israel offered an apology over the raid in 2013, gave permission for Turkish aid to reach Gaza through Israeli ports and in 2016 paid $20 million (Dh73.4m) to the families of those killed.
A legal team representing Comoros, where the Mavi Marmara was registered, took legal action against the Israeli government to the ICC in May 2013.
Prosecutor Fatou Bensouda said in 2014 that she would not prosecute Israel over the incident because it was "not of sufficient gravity"/
That meant the case could be determined as inadmissible before the ICC.
Ms Bensouda reaffirmed the decision in 2017 after judges said she must take another look at the case.
Although she has again been asked to reconsider, she retains the ultimate decision as to whether or not to initiate an investigation.
But Ms Bensouda was not spared criticism by her ICC colleagues, who said she incorrectly assumed that she could disagree with the legal terms set out by pre-trial judges when making her decision.
"The unfortunate language used by the prosecutor to express her disagreement demonstrates that she was entirely misinformed as to what was required of her," appeals judges said on Monday.
Ms Bensouda, who is due to step down as ICC prosecutor in 2021, has faced criticism in recent months after other cases collapsed.
Stoke White, the law firm representing Comoros, said Ms Bensouda should "waste no further time in opening an official and full investigation to get to the truth of Israel's actions".
"Victims have renewed hope that the ICC will deliver justice and accountability," the company said.
Gulden Sonmez, acting on behalf of the Comoros, said the ICC Appeals Chamber had made a strong decision, and he urged the public not to forget the plight of blockaded Palestinians in Gaza.
"Mavi Marmara lawsuits are a necessary challenge in the field of law," Ms Sonmez wrote on Twitter.
“But let us not forget that the deadly blockade of Gaza and the Palestinian occupation continues.”
Dr Christine Schwobel-Patel, associate professor at Warwick Law School, said: "One of the main issues at play here is the squabbling between the organs of the ICC, mediated through different parties.
"The office of the prosecutor and the judicial divisions have been engaged in power struggles from day one.
"This squabbling does not only look bad for a court losing legitimacy because of its alleged anti-African bias and inability to see cases through the system in a timely and fair manner.
"More importantly, this is problematic for the victims of the situations. Their hopes rise and fall with this back and forth too.".
Dr Schwobel-Patel said that politics was also at play in the flotilla dispute, seeing it as an invitation for the ICC to consider the Palestine-Israel conflict "by using this incident as a springboard".
"However, those who are hopeful in this regard, particularly pro-Palestinian activists, are knocking at the wrong door," she said.
"The ICC has shown very little appetite to oppose strong states.
"Most likely, the office of the prosecutor will again refuse to open the investigation, but base the argument more explicitly on the pre-trial chamber’s information, therefore meeting the legal-technical shortcomings and continuing to circumvent the political issues."