Ryan Passey died after being knifed in Chicago's in Stourbridge in 2017.
Kobe Murray, who was later cleared by a jury, admitted stabbing Mr Passey but said he did so in self-defence.
Mr Passey's family, who insist they were failed by the criminal justice system, said they were taking the civil route with the hope of securing public recognition that the 24-year-old was unlawfully killed.
Civil Prosecution Papers have now been served to Kobe Murray after the process was undertaken by Ryan's father Adrian Passey in August this year.
Friend and family spokesman Jason Connon said: "Our civil prosecution is just one part of a number of actions we will be taking in the coming months ahead in our fight to finally get justice for Ryan.
"This year has been particularly difficult with the impact of Covid on our campaigning activities, but we maintained from day one, following the reprehensible and inconceivable acquittal verdict delivered at our trial, that we would fight on for the rightful justice Ryan deserves and no matter difficult or how long that takes, we will never give up.
"It is in the interest of the whole of our society and our criminal justice system, we fight on to right this terrible wrong and allow Ryan’s parents some opportunity to be able to grieve properly and to try and move on from the psychological, emotional, and physical damage caused by the sudden loss of Ryan, deepened even further from not receiving any form of justice to date."
Mr Connon said the family wanted to thank their legal team – Barrister Matthew Stanbury, from Garden Court Chambers, and Chris Topping of Broudie Jackson Canter.
Private investigators Russ Whitfield of Liberton Investigations and Simon Bates of Artifex investigations were praised alongside members of the public who backed the Justice for Ryan campaign.