The Supreme Court is ruling today on crucial legal issues raised in high-profile damages claims brought by foreign nationals against the UK Government arising from the global war on terror.
Three of the claimants - Yunus Rahmatullah, Serdar Mohammed and Abd Ali Hameed Al-Waheed - want the go-ahead to sue the Ministry of Defence (MoD).
They say UK authorities were involved in their unlawful detention and mistreatment when they were arrested as suspected insurgents in conflict zones in Afghanistan and Iraq.
Another case involves Libyan dissident Abdel Hakim Belhaj and his then-pregnant wife Fatima Boudchar.
The couple are battling to sue former Foreign Secretary Jack Straw and an ex-MI6 officer, as well as the Government, over Britain's alleged role in their abduction in 2004 to Libya where they say they were detained and tortured.
The Belhaj family have asked for an apology and a token £1 payment from each of the defendants, who have denied liability.
The international human rights group Reprieve say the UK Government has already settled a related claim out of court by paying compensation to the al-Saadi family who were rendered to Libya just weeks after Belhaj and Boudchar.
Reprieve and the Belhaj family say the abduction involved a joint MI6-CIA operation following the 2004 "deal in the desert" in which the government of Tony Blair re-opened diplomatic links with Gaddafi.
According to Reprieve, part of the deal involved the illegal kidnapping and flying of Libyan dissidents to Tripoli.
Supreme Court justices are having to decide key preliminary legal issues which could either bar - or open the way - for claimants in all the cases to sue the UK Government for compensation, potentially triggering a new wave of similar claims from conflict zones.
Government lawyers are asking the seven justices - court president Lord Neuberger sitting with Lady Hale, Lords Mance, Clarke, Wilson, Sumption and Hughes - to rule the claims should be barred under state immunity and the "act of state" doctrine.
They contend the doctrine prohibits domestic courts sitting in judgment on the acts of foreign governments, or hearing claims made against the UK Government relating to state activities conducted overseas in pursuit of government policy.
Military sources say a ruling adverse to the Government could affect the ability of British soldiers to assist in UN peacekeeping operations in "non-international armed conflicts".
Pakistani-born Yunus Rahmatullah was initially detained by UK forces in Iraq in 2004 before being transferred to US forces and held for more than 10 years without charge or trial. His lawyers allege he suffered torture and serious mistreatment.
He was eventually released in Pakistan on June 17 2014 and now claims damages for alleged wrongdoing by the MoD and breaches of his human rights.
Serdar Mohammed, an Afghan farmer, was captured by UK forces on April 7 2010 in Afghanistan on suspicion of being a senior Taliban commander and bomb- maker and is claiming damages under the 1998 Human Rights Act.
He was detained in an operation in which three British servicemen were wounded and two insurgent suspects killed.
The British troops were part of the International Security Assistance Force - a multinational force under Nato command established by the UN Security Council to fight the Taliban insurgency.
Mohammed was held from April 7 to July 25 2010 and then transferred into Afghan custody.
Both the High Court and Court of Appeal have ruled that only his initial detention for 96 hours was lawful, and his continued detention on UK military bases beyond that period was unlawful and he should have been either handed over to the Afghan authorities or released.
He was subsequently convicted in Afghan courts of offences related to insurgency in Afghanistan and sentenced to 10 years' imprisonment.
Released under an amnesty deal in 2014, Mohammed said he was tortured into giving a false confession.
Abd Ali Hameed Al-Waheed, an Iraqi citizen, was detained without charge by UK forces in Iraq in 2007 in the aftermath of the coalition invasion and overthrow of the Ba'ath Party government of Saddam Hussein.
Al-Waheed was detained without charge just over six weeks - February 11-March 28 2007 on the grounds that the move was imperative "for reasons of security".
Al-Waheed's lawyers say the move was unlawful and in breach of his right to liberty under Article 5 of the European Convention on Human Rights.