Hundreds of Palestinians held in Israeli prisons without charge or trial have launched an open-ended boycott of Israel's military courts.

In a joint statement announcing Thursday's move, 450 people jailed under Israel's controversial practice of administrative detention said their decision had been taken "collectively and unanimously".

"The core of resisting administrative detention policy comes from boycotting this Israeli legal system," the detainees, held in various locations, said in the statement.

"We put our faith and trust in our people, their power and institutions, and in the civil society which will not leave us alone in this fight."

The prisoners also urged the Palestinian Authority to take the issue of administrative detention to the International Criminal Court (ICC) "as soon as possible".

Lawyers' backing

Administrative detention is a vague legal process that allows Israel to imprison Palestinians from the occupied West Bank and Gaza Strip without charge or trial for an indefinite period. These arrests are based on undisclosed "secret evidence".

In recent months, there has been a spike in the number of arrests made without charge, especially as protests across the occupied territories - including East Jerusalem - erupted over a US decision to recognise Jerusalem as Israel's capital.

Sahar Francis, director of Addameer, a Ramallah-based prisoners' rights group, said there were three stages to the prisoners' move.

"The first is to boycott the reaffirmation hearings, which endorse detention based on an undisclosed national security threat," Francis told Al Jazeera.

"Then, they will boycott the appeals court, which is a military court, but there for lawyers to appeal the reaffirmation decisions," she said.

"And the final stage is to boycott the option to appeal to the constitutional court."

Lawyers representing the detainees have also agreed not to attend court hearings.

"We have agreed to adhere to the prisoners' wishes and have a moral obligation to do so," Amjad al-Najjar, a lawyer for the Hebron-based Palestinian Prisoners Club (PPC), told Al Jazeera.

Both Addameer and PPC currently oversee at least 40 administrative detention cases.

Throughout the duration of the boycott, detainees will be risking losing access to family visitation rights and prison canteens, as well face the possibility of solitary confinement as a means of reprisal.

Refusal to attend court hearings may also result in the forceful transfer of prisoners, which constitutes "kidnap", said al-Najjar.

"This is what happened in 2014, the last time administrative detainees decided to strike against the practice," he said.

During their forced transfer to hearings, detainees are often beaten, verbally abused and "dragged in chains", according to al-Najjar.

Other risks include courts going ahead with hearings even without the presence of the prisoners and their lawyers, in violation of international standards, Addameer's Francis explained.

Rallies in solidarity

Administrative detention is subject to renewal every six months. It is authorised by a military order as opposed to judicial decree.

Historically, the longest detention period of this kind lasted for eight consecutive years during the first Intifada, or mass uprising, which began in 1987.

Francis said some people have spent a total of 10 years in administrative detention, but over a span of 15 years – so they are "briefly released for about four months in between".

Occasionally, some detainees are forced to go into exile as a condition for their release.

The prisoners' action has the backing of a number of groups, including the Palestinian Committee of Prisoners' Affairs and the Palestine Liberation Organisation's (PLO) Central Council, the second-highest Palestinian decision-making body.

Demonstrations in solidarity with the detainees are expected to take place across various cities in the territories, including Ramallah, Hebron and Nablus.

The detainees, which include three women and a 17-year-old boy, are held either in Ramallah's Ofer jail or in at least three different detention facilities inside Israel.

This is in direct contravention of international law, which prohibits Israel as an occupying power from transferring Palestinians from the occupied territories.

Such unlawful deportation constitutes a war crime under the Rome Statute of the ICC.

Among those held are seven parliamentarians, including 54-year-old Khalida Jarrar, a deputy at the Palestinian Legislative Council and a key figure in the Palestinian Front for the Liberation of Palestine - a leftist political party that Israel considers a "terrorist" group.

This is not the first time an attempt aimed at abolishing administrative detention has been made.

In 2002, following the start of the second Intifada, a strike lasted for three months, while in 2014 a similar effort that went on for 63 days ended without any results.

According to al-Najjar, several agreements were signed between rights groups and prison administrations, but these deals were "immediately broken" by Israeli authorities who run the prisons.

Under these agreements, administrative detention cannot be renewed for more than three times in a row. Upon the third renewal, the Israeli army is expected to provide prisoners and their lawyers with a list of accusations so "they know what they're up against".

"It's the only way to build a case, but, of course, this doesn't happen," said al-Najjar.