Tristan Anderson, 38, was critically injured during a Palestinian protest in the West Bank village of Naalin in March. Amir Moran, spokesman for Israel's Tel Hashomer hospital, where Anderson is being treated, said his condition has not changed.

No criminal intent

Justice Ministry spokesman Ron Roman said the investigation found no criminal intent in harming Anderson. The investigation was opened in May and closed several weeks ago, but results were made public only Sunday.

Human rights groups say Anderson's case highlights how Israeli forces are not held accountable because incidents of harm against Palestinians and their supporters are rarely investigated and few reach prosecution.

"The number of civilians harmed and injured and then the number of investigations - a small minority of cases, and a tiny number of prosecutions - point to a very, very clear picture of impunity," said Sarit Michaeli of Israeli rights group B'Tselem.

Anderson's family was not immediately available for comment.

Anderson was among a group of about 400 Palestinian and international demonstrators who gathered March 13 in Naalin near the wall Israel is building along its border to keep Palestinians out.

Some of the protesters threw rocks at troops, who used riot gear to quell the unrest, the military said at the time, without elaborating.

Israel defends barrier

Israel says the 425-mile barrier is necessary to keep Palestinian attackers out. The barrier juts into the West Bank in some places, leaving about 10 percent of the territory on the Israeli side. Palestinians view it as a land grab.

Before going to Israel, Anderson was one of the tree-sitters who occupied a grove next to UC Berkeley's Memorial Stadium until September 2008 in an unsuccessful bid to stop the university from clearing the trees to make room for an athletic center.