Armstrong’s mistake was in not joining the postal workers union, if he was a member they would have rallied around him to ward off those evil meanies out to besmirch the reputations of all the fine underpaid postal workers.

Lance Armstrong boosted the levels of naturally occurring substances in his body enough to win, but not enough to fail the blood tests. Floyd Landis boosted his testosterone levels to unnatural levels high enough to get caught.
http://www.geek.com/news/how-lance-armstrong-beat-the-drug-tests-1536719/

Punishing Lance Armstrong within the sport of cycling seems reasonable, but I don’t see how the USPS brand was damaged. They benefited more from the publicity of the unfair wins than they would have if their cycling team didn’t win.

1. Suit was already brought, 2 years ago, by Floyd Landis.
2. US Gov by way of DofJ is joining it; not starting it.
3. This is about US government going on record; having history not question/wonder whether Armstrong/Team USPS was state-sponsored international pro sport cheating — for the history books being read 50 years from now (anyone remember East Germany of the 1960’s-70’s?)
4. If DofJ does not join the existing suit, history recorders will say it begs the question “why not?” (“something to hide?; maybe all coordinated by the state?”)
5. DofJ has to join the suit to ward that off; be categorical about it.
6. If you are going to act all righteous and indignant, you may as well go whole hog and have it play out in public courts (and not do a quiet settlement; that just leaves the same old questions)
7. This is not (primarily) about the money — both US government and Lance Armstrong got tons, last I looked
8. Floyd Landis? Well, yes, he could probably use his 25% cut of any award, as the whistleblower.
9. Lance had a penchant for making enemies (e.g., see Floyd Landis)
10. Some US senators and Congressmen were humiliated putting their necks on the line (some) by taking Lance’s side during the USADA investigation, going so far as to petition to have it shut down (believing Lance’s “witch-hunt” claims). They may have been pushing for this as well (yeah; they may have got a little peeved-off).

Lance liked to think himself as a smart guy. But he selected an agency of the government of the United States of America (USPS), one of the few established directly in the Constitution, to launch his racketeering ventures. He then hand-picked U.S. citizen cyclists to make up the bulk of this teammates. They turned out to be constitutionally hampered in any attempts to protect him (i.e., “be quiet”) when subpenaed.

Oops.

Not too smart by halves.