The British Olympic Association on Tuesday formally submitted its application to the Court of Arbitration for Sport (CAS) to challenge the World Anti-Doping Agency's declaration that the stance is "non-compliant".
Millar was banned from cycling for two years in 2004 for admitting to doping offences. Under current BOA rules, this qualifies him for a lifetime ban from Olympic competition. It is the only Olympic Committee in the world to hold such a stance.
Millar is one of three British athletes affected by the ban, along with sprinter Dwain Chambers and shot-putter and discus thrower Carl Myerscough.
With Olympic selection on the horizon for the London Olympic Games, both the BOA and WADA agree that the issue needs to be settled quickly – the CAS are now expected to issue a ruling in April 2012.
BOA chairman Lord Moynihan told the BBC that: "The reality is it's WADA that have come after us and said 'we deem you to be non-compliant' so we are the reactors in this case.
"It's regrettable we have got to take this step. To me it was completely wrong of WADA to mix up sanctions with our selection policy which has been in place longer than WADA has been in existence but that's their choice and we are defending our position."
Last month, Millar said that he did not wish to challenge the BOA's ruling.
"There are certain fights I don't want to fight and that was one of them.
"I just don't fancy being vilified any more. It's been a tough couple of years."