AUSTIN, Texas -- The Justice Department laid out its case in a lawsuit against Lance Armstrong on Tuesday, saying the cyclist violated his contract with the U.S. Postal Service and was "unjustly enriched" while cheating to win the Tour de France.
The government had previously announced it would join the whistle-blower lawsuit brought by former Armstrong teammate Floyd Landis. Tuesday was the deadline to file its formal complaint.
The Postal Service paid about $40 million to be the title sponsor of Armstrong's teams for six of his seven Tour de France victories. The filing in U.S. district court in Washington, D.C., says the USPS paid Armstrong $17 million from 1998 to 2004.
The lawsuit also names former team director Johan Bruyneel and team management company Tailwind Sports as defendants.
The financial costs for Armstrong and Bruyneel could be high. The government said it would seek triple damages assessed by the jury.
"Defendants were unjustly enriched to the extent of the payments and other benefits they received from the USPS, either directly or indirectly," the complaint said.
Armstrong, who in January admitted using performance-enhancing drugs after years of denials, has argued that the Postal Service's endorsement of his team earned the government agency far more than it paid him.
Armstrong attorney Elliot Peters called the government's complaint "opportunistic and insincere."
"The U.S. Postal Service benefited tremendously from its sponsorship of the cycling team. Its own studies repeatedly and conclusively prove this. The USPS was never the victim of fraud. Lance Armstrong rode his heart out for the USPS team and gave the brand tremendous exposure during the sponsorship years," Peters said.
Paul D. Scott, the lawyer representing Landis, issued a statement Tuesday night.
"Mr. Landis is pleased to see the United States take this important step toward recovering taxpayer dollars lost to fraud," Scott said.
"It plainly does more damage than good to the policies, programs and international standing of the United States for it to be associated with a cycling team that dopes to win. The fact that the team's fraud was concealed for many years does not take away from the fact that the United States was harmed. Even if the USPS received some ephemeral media exposure in connection with Mr. Armstrong's false victories, any illusory benefit from those times will be swamped over time immemorial by the USPS forever being tied to the largest doping scandal in the history of sports."
The government must prove not only that the Postal Service was defrauded, but that it was damaged somehow.
Previous studies done for the Postal Service concluded the agency reaped at least $139 million in worldwide brand exposure in four years: $35 million to $40 million for sponsoring the Armstrong team in 2001; $38 million to $42 million in 2002; $31 million in 2003; and $34.6 million in 2004.
The formal complaint against Armstrong appears to rely heavily on evidence and statements supplied by Landis and gathered by the U.S. Anti-Doping Agency for its 2012 investigation that exposed a doping program of the USPS team. Armstrong has been banned from sports for life and stripped of his seven Tour de France victories.
Bruyneel, who lives in London, also has been charged by USADA with doping violations but is fighting that case in arbitration.
The government notes the contract with the Postal Service required riders to follow the rules of cycling, which included bans on performance-enhancing drugs and methods. Armstrong now admits using steroids, blood boosters and other illegal performance-enhancing drugs and measures to win.
By breaking the rules and covering it up, Armstrong and Bruyneel committed fraud against the U.S. government, the complaint said.
The complaint said that for years, team officials assured the Postal Service that the team was not doping.
Armstrong had been the target of a federal criminal grand jury, but that case was closed without charges in February 2012. Armstrong has previously tried to settle the Landis whistleblower lawsuit, but those talks broke down before the government announced its intention to join the case.
Armstrong is also fighting a lawsuit from Dallas-based promotions company SCA to recover about $12 million it paid him in bonuses, and a lawsuit from the London-based Sunday Times, which wants to get back $500,000 it paid him to settle a libel case.
Information from The Associated Press and ESPN.com's Bonnie D. Ford was used in this report.