The family of Pc David Rathband have lost their High Court negligence claim against the shot policeman's employer Northumbria Police.
The officer was blasted twice and left for dead by gunman Raoul Moat just minutes after the maniac had phoned 999 to say he was hunting for police.
Pc Rathband was blinded in the July 2010 shooting, and took his own life in February 2012.
His siblings brought the High Court claim, saying if senior officers had warned him, he would not have been sat stationary in his patrol car on a prominent Newcastle roundabout above the A1.
Northumbria Police defended their actions that night, saying if commanders had rushed orders another serious incident could have occurred.
Mr Justice Males handed down his judgment at Newcastle's Moot Hall.
The claim was brought by the officer's twin brother Darren and sister Debbie Essery, as executors of his will, and they have stated should they win, any compensation will be paid to his two children.
The judge said the claimants must also pay the force's costs, with an interim payment of £100,000 due within 21 days.
No members of Pc Rathband's family were in court, as the parties had been made aware of the judgement before the ruling was handed down by the judge.
Mr Justice Males said it was less than nine minutes after the 999 call that Moat shot the unarmed and defenceless officer in his car.
"Pc Rathband suffered horrific injuries, including the loss of his eyesight," he said. "It is surprising that he was not killed."
He said the claimants' case was that, if he had been warned, Pc Rathband would not have been, in his own words, "a sitting duck".
They said Superintendent Jo Farrell, in charge of the operation that night, was negligent in failing to issue a warning.
The judge said the 15-minute period between Moat ringing 999 and him leaving Pc Rathband for dead had been the focus of "intense forensic scrutiny" during the eight-day High Court hearing.
He said it was a fast-moving and unprecedented situation for the commanders.
He added: "I am acutely conscious that it is easy to be wise after the event and that the dangers of hindsight must be avoided."