The Palestinians take their challenge to Israel's West Bank barrier before the World Court today after a suicide bombing Israeli officials said proved the need for building the vast network of walls and fences.
The Hague-based UN tribunal will hold three days of hearings on the legality of the barrier, which Israel calls a bulwark against militant attacks and Palestinians condemn as a grab for land they want for a state.
At stake is not only an international ruling on the barrier but world opinion in a case that underlines the paralysis of Middle East peacemaking after more than three years of violence.
The hearings stem from a Palestinian request - backed by the United Nations General Assembly - to decide whether Israel is legally obliged to tear down its partially built barrier. About 180 kilometres of the planned 730 km (435 miles) construction has so far been built.
The Israeli government has refused to attend the hearings, calling the case political and beyond the court's jurisdiction.
But Israel won't remain on the sidelines. A rescue service sent the skeleton of a Jerusalem bus, in which a Palestinian suicide bomber killed 11 people last month, for display outside the court as grim evidence of what Israelis have endured.
The Foreign Ministry dispatched a team to deal with the press, and hundreds of Israeli demonstrators, including relatives of victims of suicide bombings, were flown in.
Israeli Defence Minister Mr Shaul Mofaz responded to Sunday's bombing in Jerusalem with a vow that "we will continue to build the fence in accordance with the government's decision".
In overnight operations, Israeli forces demolished the bomber's family home near Bethlehem - a standard reprisal - and arrested 11 suspected militants in the area.
Palestinian lawyers will tell the judges the barrier is illegal under international law for absorbing chunks of occupied land, including loops around Jewish settlements, and for hardship caused to the Palestinian population, officials said.
They will argue the barrier should be dismantled or shifted to follow Israel's boundary with the West Bank before it was seized along with the Gaza Strip in the 1967 Middle East war.
To dramatise their case, Palestinian demonstrators will build a mock barrier and demolish it outside the court.
About a dozen countries, including Saudi Arabia, Jordan, South Africa, Algeria and Cuba, are due to present oral arguments in support of the Palestinian position.
The United States, Britain, the European Union and many Western countries have criticised the route of the barrier but are joining Israel in shunning the hearings. They oppose the court's involvement, saying it may interfere with peacemaking.
A decision by the court could take several months.