Usada also gave him a life ban for what it described as "the most sophisticated, professionalised and successful doping programme that sport has ever seen".
The organisation released a 1,000-page report last October, which included sworn testimony from 26 people, including 15 riders with knowledge of the US Postal Service Team, for which Armstrong competed.
Cooke attacks cycling drug cheats
Armstrong also later resigned as chairman of the Livestrong Foundation, the cancer charity he created.
But his lawyer, Tim Herman, has described the Usada report as a "one-sided hatchet job" and the cyclist himself has accused the agency of offering "corrupt inducements" to other riders to speak out against him.
Armstrong won the Tour de France for seven successive years between 1999 and 2005 after overcoming testicular cancer.
"Perjury is a statement under oath that is false and carries a potential prison sentence of up to five years," said Slotnick.
"But in most cases, with exceptions such as murder, the Statute of Limitations means you have five years in which you can be prosecuted from the date of any crime. After that time, a defendant can go to the judge and say it's too late."
Former teammate Floyd Landis - who was stripped of his 2006 Tour de France title for doping - has filed a federal whistle-blower lawsuit accusing Armstrong of defrauding the US Postal Service, which paid more than £18.7m to sponsor the team Armstrong competed for.
The US Department of Justice is reportedly considering whether to join the lawsuit against him and Armstrong's lawyers are said to be in negotiations to settle the suit.
In addition, the Sunday Times is already suing Armstrong for £1m over a libel payment to him in 2004 after the newspaper alleged he had cheated.
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