Aharon Barak, a former president of Israel’s Supreme Court, has resigned from his role as ad hoc judge on an International Court of Justice (ICJ) panel weighing a genocide allegation filed over the country’s military campaign in Gaza, officials said, Reuters reports.

In a resignation letter dated June 4 and republished by Israeli media, the 87-year-old Barak cited unspecified personal and family reasons for his decision.

Under the ICJ’s rules, a state that does not have a judge of its nationality already on the bench can choose an ad hoc judge to sit in their case. It was not immediately clear who Israel might appoint to replace Barak.

In a statement thanking Barak for his service at the Hague, Israeli President Isaac Herzog said, “We will continue to stand steadfast against the evil, hypocrisy and libels cast against the State of Israel and IDF (Israel Defence Forces).”