His mother and sisters have launched the action against Ewan’s former employers, Lothian & Borders Fire & Rescue Board, because they believe mistakes were made which cost Ewan his life.
Ewan Williamson was 35 when he died.
Thousands of friends and workmates lined the streets of Edinburgh to pay their respects on the day of his funeral.
In a statement, the family said: “Almost three years have passed since Ewan lost his life and we have waited patiently for the authorities to investigate what happened and either prosecute those they hold responsible or hold a Fatal Accident Inquiry into Ewan’s death.
“Despite the passage of time, we still do not know all the facts or why Ewan died.
“The night we lost Ewan turned our lives upside down. Nothing can ever replace him but we feel that we cannot move on until we know what happened to Ewan and any lessons which should be learned and applied from that night are put into practice.
“The justice system is taking far too long and we simply cannot wait any longer. Enough is enough.”
Ewan Williamson is the only firefighter in the history of Lothian and Borders Fire and Rescue Service to die tackling a blaze.
The results of an official investigation into what happened during the fire at the Balmoral Bar in July 2009 have yet to be made public.
Roddy Robertson, FBU Executive Council Member for Scotland said: “The Fire Brigades Union have supported the Williamson family throughout their ordeal. We share their interest in what happened that night and why Ewan died.
“Our members have a professional job to do and it can sometimes be dangerous. If there are lessons to be learned from Ewan’s death then there should not be delays of the sort we have seen here in learning them. The Crown Office now needs to reach an early decision on what they are going to do with Ewan’s case and we are pressing for that to happen.
“In the absence of any Fatal Accident Inquiry or prosecution after this length of time it is necessary for both the Williamson family and the future safety of Firefighters that this action is taken.”
Senior Partner at Thompsons, Solicitors, Syd Smith, is representing the family in their action at the Court of Session in Edinburgh.
He said: “The Williamson family have waited long enough for action and answers regarding Ewan’s tragic death. That is why we are having to launch a legal action for damages.
“The length of time it is taking the Crown Office to make a decision on how to proceed is frankly unacceptable.
“Our firm sees case after case where somebody has died and these delays then take place. Everybody understands that fatal accidents have to be fully and properly investigated but even in difficult or complicated cases it should not take this length of time.”