Armstrong is a ferociously competitive beast, but faced with a process he saw as blatantly unfair and stacked against him, he refused to take part in an arbitration with USADA over the charges.
USADA, the agency that handles drug testing and enforcement for Olympic-level and other elite athletes who compete in global events like the Tour, refused to provide the names of the dozen witnesses slated to testify against him, as is required in U.S. courts. “From the beginning, we have challenged USADA’s motives, methods and authority to proceed with a so-called conspiracy charge against Mr. Armstrong,” his attorneys said in a statement.

With Armstrong’s decision not to arbitrate, his victories have vanished.Certainly, his legend as a cyclist, once tainted, is forever scarred. It was a great one too. Surviving a cancer that had spread from his testicle to his lungs and brain,
Armstrong resolutely defended himself, reminding his critics that he never failed a drug test during his career — 560 in total, according to the Wall Street Journal.So Armstrong decided he was finished defending himself
More than that, he bitterly resents being singled out by USADA and its leader, Travis Tygart, for what he labeled “an unconstitutional witch hunt” — a pursuit that has cost Armstrong millions in legal fees. He was also targeted by federal investigators who spent three years and millions of taxpayer dollars pursuing charges that Armstrong somehow defrauded the government by winning the Tour de France as the leader of the Posties while using PEDs.
When the federal court threw out his suit, Armstrong figured he had no chance in USADA’s court. The agency that had been after him for more than 10 years now stood, in his view, as judge, jury and executioner.Instead, he will take his case to the court of public opinion. And there we can all judge him.

Watched this news over the weekend. Lance Armstrong is said to have failed a dope test and has now been stripped of all previous medals. What's wrong these US athletes?

One of his former teammates already came forward last year to seeing illegal substances in his refrigerator, as well as witnessing him use them twice. There were other teammates of his who were ready to come forward against him too.
He knew it was a no-win situation for him and dropping the charges would save him from the embarrassment he would have to go through.