How about this source, the actual human rights organization that produced the report?

hamoked.org/document.php?dID=Updates2136

Administrative detention constitutes a draconian violation of a person’s rights to liberty and due process. International humanitarian law permits this detention without trial only as an exceptional measure when there is a substantial security threat that cannot be otherwise avoided. But Israel’s use of this measure toward Palestinians is not exceptional at all; Israel holds hundreds of Palestinians from the West Bank in administrative detention for periods of months and even years. Furthermore, administrative detention orders are based on “classified material” such that the detainee has no way to refute the allegations against them. And the Israeli military can extend the period of administrative detention without limit. The infringement of rights of administrative detainees is exacerbated by the fact that many of them are held inside Israel, in blatant violation of the Fourth Geneva Convention, which prohibits the transfer of inmates outside the occupied territory.