The men were killed in Iraq and Afghanistan in the last four years
Four families of servicemen killed in Snatch Land Rovers in Iraq and Afghanistan are to sue the Ministry of Defence, the BBC has learned.
They claim the vehicles are too lightly armoured to cope with the weapons used against them and that the MoD was negligent in allowing their use.
However, the MoD maintains the vehicles are vital equipment and suitable for the jobs they must perform.
Since 2003, some 37 UK personnel have been killed while using the vehicles.
The lightly-armoured Snatch Land Rovers are used on operations where troops need quick land transport.
They are fortified with armour to offer protection against explosions and ballistics, but have been criticised for offering insufficient protection against roadside bombs.
The Snatch Land Rover was specifically designed for Northern Ireland
Last year, the then Defence Secretary, John Hutton, ruled out a public inquiry into their use and announced plans to spend £700m on new, upgraded vehicles.
The families are claiming the MoD's failure to provide adequate protection was a breach of their sons' human rights, as well as claiming negligence.
They say last month's Court of Appeal ruling that the Human Rights Act can apply to the battlefield supports their cases.
Those taking action are the families of Pte Lee Ellis, from Manchester, who died in Amara in Iraq in Feb 2006; Marine Gary Wright, of Stirlingshire, killed in Afghanistan in October 2006; L/Cpl Kirk Redpath, of Essex, killed in Iraq in August 2007; and Pte Phillip Hewett, of Tamworth, also killed in Iraq two years earlier.
The lawyers acting for them say they expect other claims will be brought in the future.
The Ministry of Defence confirmed four compensation claims had been received over the past 14 months following deaths involving Snatch Land Rovers in Iraq and Afghanistan.
A department spokesman said: "The MoD pays compensation wherever there is a liability to do so. In these cases we remain profoundly aware of the enduring grief of the four families who lost their loved ones in combat."