The families of four soldiers killed in Iraq are fighting an attempt by the Ministry of Defence to have their compensation claims struck out because of combat immunity.
The three-day hearing before Mr Justice Owen in London has been brought by relatives of Corporal Stephen Allbutt, Private Phillip Hewett, Private Lee Ellis and Lance Corporal Kirk Redpath.
Cpl Allbutt was killed in March 2003 when his tank came under friendly fire by another British tank in southern Iraq.
Lawyers Leigh Day & Co, who represent his widow Debi, have said the MoD's stance meant it owed no duty of care to its soldiers during the "heat of battle".
The firm said it is "vigorously challenging" the MoD's case which it described as a "travesty of justice".
Pte Hewett, whose claim is being pursued by his mother Susan Smith, was killed in Al Amarah in July 2005.
Karla and Courtney Ellis, the sister and daughter of Pte Ellis, are bringing a claim over his death in the same area in February 2006, while Colin Redpath's claim relates to the death of his son Kirk near Basra in August 2007.
Their three actions challenge the use of Snatch Land Rovers in Iraq and Afghanistan which, they say, provide little or no protection against improvised explosive devices.
Civil liberties solicitor Jocelyn Cockburn, representing Snatch families, said: "The MoD's approach throughout this long process has been to deny that Snatch Land Rovers were inadequate. This was in the face of evidence from soldiers on the ground that they were unsafe.
"This approach has served to spur the Snatch families on to seek justice and they have been assisted by wide public support."