Belize and Madagascar are among the nations who are testifying against Israel’s security barrier at the hearing in the International Court of Justice at The Hague on Tuesday.
Other countries presenting testimony to the judges include Cuba, Malaysia and Indonesia.
Israel, some 30 Western countries and Russia are boycotting the hearing.
They say the court has no jurisdiction over the issue, and argue it is damaging itself by getting involved in politics.
The Palestinian delegation was the first to appear before the judges. Its case was presented by top international lawyers and its permanent representative at the United Nations Na’sir Al-Qidwa.
Thousands of people are demonstrating outside the courthouse; pro-Palestinian and pro-Israeli groups are not permitted to protest at the same time.
The anti-barrier lobby calls the buffer a racist wall, and says it’s a precursor to a permanent border between Israel and any permanent Palestinian state. They object to parts of it being constructed in post-1967 territories.
The pro-Israeli group at The Hague is staging silent vigils with protesters carrying photographs of some of the 935 Israelis killed by Palestinians during the past three years.