The number of Palestinians held in Israeli prisons without trial has risen by some 50 percent over the past year and, with several of them on hunger strike for more than a month, they are at the forefront of what Defense Minister Ehud Barak recently called “increasing disquiet” among Palestinians in the West Bank.

Administrative detention — incarceration without trial — is used as a preventive arrest, in advance of a crime, and it is not illegal. According to Article 78 of the Fourth Geneva Convention, an occupying power may, “for imperative reasons of security,” subject people to internment.

But it is, by all accounts, a harsh measure. Opponents refer to it as a form of “torture”; proponents deem it an effective terror-fighting “tool.” Perhaps on account of its nature — the detainee is never formally charged with a crime, never stands trial, and never knows the full duration of his or her continually renewable term of incarceration – it has been met with staunch Palestinian resistance.

Khader Adnan, a baker by trade and an alleged member of Islamic Jihad from the village of Arabe near Jenin, was administratively detained for the third time on December 17, 2011. The following day, he stopped taking food and fluid. Sixty-six days later, he had lost his hair and some 30 kilograms and was close to death. Israel, fearing the repercussions of a death behind bars — the first intifada was sparked by a traffic accident — decided to “offset the days in which the appellant was detained for the purpose of a criminal investigation prior to his administrative detention from the period of the current administrative detention order” and set a firm April 17 date for his release. Adnan, in return, agreed to end the strike.

His release falls on Palestinian Prisoner Day.

Several weeks later a similar arrangement was reached with Hanaa Shalabi, another alleged Islamic Jihad member, who had gone 43 days without food and drink.

Anat Litwin, the director of the prisoners and detainees department at Physicians for Human Rights, said that there are currently eight hunger strikers in Israeli prison. Seven of them are administrative detainees and almost all have been striking for over a month.

In solidarity with their struggle and in protest of the conditions under which they serve their own terms of incarceration, some 1,600 Palestinian prisoners, roughly 30 percent of the total Palestinian prisoner population in Israeli jails, will begin a hunger strike on April 17. According to Litwin, Hamas and Islamic Jihad prisoners will be striking collectively, by decree, and they will be joined by individual Fatah and PFLP members.

Their struggles are being closely watched in the West Bank, where terror activity has shriveled, but the desire to shirk Israeli rule remains strong.

On March 26, Marwan Barghouti, a man many consider to be a Palestinian leader-in-waiting and almost surely Fatah’s only true chance of sustained leadership in the West Bank, smuggled a statement out of his Israeli jail cell. It was read aloud in central Ramallah like the words of a prophet.

Barghouti, a key figure behind the second intifada who is serving five life terms for murder, declared the negotiations with Israel “an illusion” and called on Palestinians to reenact the Arab Spring across the West Bank in a show of “wide-scale civil resistance.” His letter earned him a week of solitary confinement in prison. But it also illustrated the challenges facing Israel as it tries to govern, contain and thwart anti-Israel violence among a population of two and a half million malcontent Palestinians in the West Bank.

To do so, Israel uses carrots and sticks. And one of those measures, most odious to Palestinians and a necessary evil to Israelis, is administrative detention.

The process starts with the Shin Bet. An agent passes intelligence on to the regional commanding officer, who has the authority to sign an administrative detention order. The wanted individual is arrested, jailed, brought before a judge. The term of the detention is generally six months. It can be renewed indefinitely. Some Palestinians have spent over 50 months in administrative detention. Nine Jews have been detained, but never for more than a single six-month term.

The army’s request is generally approved. At times, Israel has imprisoned thousands of Palestinians in this manner. At other times, such as during Menachem Begin’s tenure as prime minister, the number has dipped to as low as three. Currently there are 319 such prisoners. Those are the facts. Interpretation of them varies wildly.

“The bottom line is that this is a legal tool used when there are clear-cut threats to Israeli security and there is no other recourse,” said Captain Eytan Buchman of the IDF Spokesperson’s Office.

Brig. Gen. (Ret.) Shalom Harari, a veteran of the IDF’s military intelligence directorate and formerly the head of the Department of Palestinian Affairs at the Defense Ministry, places the matter in more illustrative terms. “There’s such a thing as a tool box. This is a tool. It’s best not used. But if you take the quarter-kilo hammer and it doesn’t work, then you take the kilo hammer.”

Both officers point to the case of Khader Adnan as an example. In an October 2007 video that the IDF has released, he is seen eulogizing a member of the Jihad’s Quds Brigades. His voice hoarse, he yells into a microphone, “Who among you is Hassan Abu-Ziad? Who among you is the next suicide bomber? Who among you will carry the next explosive belt? Who among you will fire the next bullets? Who among you will have his body parts blown all over?”

“The man is not a baker,” said Buchman, alluding to how he is sometimes referred to in the international press.

Nor, however, is there proof that he has committed a crime. An administrative detention order is signed by a judge after a Shin Bet officer, speaking privately with the military judge, brings the testimony of two incriminating sources. “This is intelligence evidence,” said Harari, “not legal evidence.” In essence, it is a form of hearsay.

At times, presumably, the intelligence is rock solid. But the widespread use of administrative detention, the regular bypassing of due process, is what irks many of the human rights groups in Israel.

Attorney Tamar Peleg-Sryck, in an article on the matter for the HaMoked – Center for the Defence of the Individual, characterized it as “a closed circle, without a crack of transparency, which does not allow the prisoner to defend himself, excuses the prosecution from the burden of proof and prevents the judge from writing a well-argued verdict.”

She further contends that some of her clients have had their administrative detention used as a recruitment tool by the Shin Bet. A man she refers to in the article as T.N. told her that, after being released from prison for weapons possession and membership in the Popular Front for the Liberation of Palestine, he was approached by a Shin Bet officer known as Captain Haggai, who told him that he could make a looming administrative detention order disappear “on condition that we would talk about certain matters and he could call me on the phone.”

When T.N. refused, he was administratively detained and then approached again by the same officer several months later.

On March 11, 2010, T.N. told the judge who weighed his administrative detention order that on February 2 he had spent six hours with the same case officer who said he “would like to help” as long as T.N. would agree to meet with him in secret, wherever convenient, “in Jenin, in Jordan, in Israel, in Iran.” When T.N. refused, the agent reminded him that he had “a family and children, and I was building a house and that if I didn’t cooperate I would be ruining my life, and he reminded me that my wife was about to give birth.”

For others, it is less dramatic but no less devastating. Samer Nemer, a 52-year-old resident of Ramallah, has been administratively detained twice for a total of 16 months. He described being awoken at 3 a.m. by 15 to 20 army troops. His eyes were bound, his hands cuffed. The trip to prison, he said during a recent phone interview, normally a 15-minute drive, took 15 hours. Several days later, in February 2008, he was brought before a judge in a military court. The reason for the detention, he learned, was membership in a proscribed organization.

Nemer is a successful businessman who deals in real estate in the Ramallah region. He also raised money for, built, and headed the academic council of the Muhammad Ben-Rashid School in Ramallah. According to the military prosecution, the school is run by the Alhansaa organization, which, it claimed, is an offshoot of Hamas. His lawyer argued that Alhansaa is not only openly supported by the PA but also by a women’s organization, and therefore he could not be a member. “They took all of the documents and found nothing,” he said.

The school teaches a Singapore curriculum in English and math and even teaches Hebrew to grades 7-10, he said. “It is not a Taliban school.”

His final incarceration ended after 10 months with a ruling from Colonel Eli Wolf, who determined that insufficient evidence had been submitted linking the accused with Hamas.

During his imprisonment, he said he lost $400,000, but — more significantly — he said, speaking of administrative detainees in general and perhaps of himself as well, the flimsy charge and the constant strain of uncertainty “kills their time, their hopes and their ambitions.”

A recent rally on one of the lawns of Tel Aviv University showed how divisive the practice has become. A mixed group of Arab and Jewish students held placards and stood behind a group of nine people, mostly girls, who were blindfolded and kneeling on the grass. This was their second protest for the release of Palestinian administrative detainees. Said Suidan, an Arab sociology and philosophy student from Haifa, said their struggle was “very similar to Ireland,” where the British use of administrative detention was fought with hunger strikes in prison and widespread civil unrest.

Opposite them, in Herzl T-shirts and cloaked in Israeli flags, were members of the rightist Im Tirzu group on campus. “The people that they want to see freed from prison,” said Maayan Spendy, a political science major from Acre and the head of the Im Tirzu group on the famously left-wing campus, “are actively involved in terror.”

The rally ended with a brief scuffle and a retreat to several of the university’s cafes.

But with Palestinian Prisoner Day coming up on April 17, followed by the commemoration of Nakba Day and Naksa Day, marking the Arab “catastrophe” and losses in 1948 and 1967 respectively, the matter of administrative detention is likely to be more bitterly contested.