The nine-judge court decided unanimously that the interrogation methods used by the Shin Bet (Israeli internal security) amounted to torture. "Shin Bet," it declared, "does not have the authority to shake a person, to force him into a [contorted] position or to kneel in a frog-like position or deprive him of sleep."
Eitan Felner, head of the Israeli human rights organisation B'Tselem, said: "This is one of the most important decisions taken by the Supreme Court in 50 years. It came despite pressure from the security forces. I believe it will be effective, because it is very specific about what is banned and doesn't give security services much leeway to evade the ruling."
The court ruling overturns a 1987 decision by a commission, which permitted the use of "moderate physical pressure" against suspects accused of planning attacks on Israel.
Mr Felner said that in practice "torture became a bureaucratic routine in all Shin Bet interrogation centres. We estimate that 85 per cent of Palestinian detainees were tortured, though many were later released without charge."
Shin Bet has normally justified torture by saying that it was used against suspects who were "ticking bombs", because they had information on impending attacks. Before 1987 the security services had repeatedly denied that torture was taking place.
Amnesty International, which has accused Israel of using legalised torture, said the court ruling was a "real milestone", but Ephraim Sneh, the deputy Defence minister, said it would damage Israeli security. "Limiting the Shin Bet's capabilities does not help protect Israel's citizens in the reality in which we live," he complained.
In future Shin Bet interrogations will have to follow the same rules as those of the police. These ban torture as well as brutal, humiliating or inhumane treatment of a suspect.
However the Supreme Court did give parliament the option of deciding "if Israel, because of its security problems, should allow the use of physical measures in interrogations that deviate from `normal' interrogation techniques".