Detention Without Trial In Israel

At Ha'aretz this is called "preventive arrests":

Senior Israel Defense Forces officers from the Central Command have been recommending the preventive arrest of dozens of extremists from the right - high-profile activists who have been campaigning against the disengagement and organizing protests designed to obstruct the army's moves.

Ha'aretz also has an interesting quote from the Women in Green:

The Women in Green (Women for Israel's Tomorrow) activist organization condemned the arrest and demanded Ofen's immediate release. "We are against administrative detention, but if Jews who pose a danger are going to be arrested, then Ariel Sharon and Shimon Peres should be arrested for threatening the very existence of the State of Israel," they said.

From Ynet's headline, you might think that Neria Ofen was a fugitive:

Right-winger surrenders to Shin Bet

Interesting what happened to Ofen's family afterwards:

Ofen was stopped with his family at the Hizma checkpoint and went peacefully with arresting security personnel.

As his wife was driving back home to Yizhar, a Molotov cocktail was thrown at her car while she was passing the northern West Bank village of Luban a-Sharqiya. There were no injuries.

Read Arutz 7's take on the matter here.