The incident took place on March 13, 2009. After Friday prayers, residents of Na'alin began a protest march against construction of a section of the separation barrier on the village's land. Also participating in the march were Israeli and foreign citizens - including Tristan Anderson, 38, an American citizen. Border Police troops used crowd-control methods, including tear-gas grenades. Anderson, a left-wing activist and photographer who has published reports of his travels throughout the world, was documenting the demonstration in Na’alin. When the marchers reached the separation barrier, a clash developed with Israeli forces. Border Police troops used crowd-control methods, including tear-gas grenades. As far as is known, Anderson was not among the demonstrators. But as he stood in the rear courtyard of the village mosque, observing what was happening, he was struck in the head by a tear-gas canister that smashed his skull, causing severe brain damage that affects him to this day, the petition claims.