At the 2006 Tour de France, he would have been the third non-European winner in the event's history, but was disqualified after testing positive for performance-enhancing drugs.

In January 2010, a French judge issued a national arrest warrant for Landis on computer hacking charges related to the 2006 Tour de France, stage 17 doping allegations.

[10] Disturbed at his son's participation in what he considered a "useless" endeavor, Landis's father tried to discourage him from racing his bike by giving him extra chores.

[citation needed] His performance led some observers to peg him as a possible team leader and future winner of the Maillot Jaune.

Landis started the 2006 season strongly, with overall wins in the Amgen Tour of California, and then in the prestigious Paris–Nice, both week-long stage races.

Landis retained his lead through the mountains with a close second-place finish to Tom Danielson on Brasstown Bald.

The original injury that led to the formation of the scar tissue was a femoral neck fracture sustained in a bicycle crash during a training ride near his Southern California home in October 2002.

LNDD is a division of the Ministry of Youth, Sport, and Social Life and is accredited by the World Anti-Doping Agency (WADA).

[35] On September 20, 2007, Landis was found guilty of doping by a 2–1 vote of the hearing committee, with Patrice Brunet and Richard McLaren in the majority, and Christopher Campbell dissenting.

[40] On August 25, 2009, The New York Times reported, "No evidence has surfaced to connect Mr. Landis or Dr. Baker to the hacking, and each has denied any involvement.

"[41] However, on February 15, 2010, it became known that a French judge issued an arrest warrant for Landis on the hacking charge in late January.

[42] During 2006 and 2007, Landis is believed to have raised about $1 million from the "Floyd Fairness Fund", established by businessman Thom Weisel.

[43] He appealed to supporters to donate "anything they could" to help him pay his reportedly $2 million legal bill, while denying his involvement in doping.

[44] Landis reached an agreement with federal prosecutors over allegations that he fraudulently solicited donations for a defense fund he set up to fight doping charges.

Landis left the OUCH team at the end of 2009, stating he wished to ride the longer, tougher stage races offered in Europe and internationally that better suit his strengths.

[46] He then raced the Tour of Southland in New Zealand in November 2009, with local team CyclingNZshop.com-Bio Sport,[48] finishing 17th overall out of a field of 95 riders.

[51] He accused several former teammates, including Lance Armstrong and George Hincapie, of using EPO and blood transfusions in the 2002 and 2003 seasons.

[52] Landis also alleged that he assisted Levi Leipheimer and Dave Zabriskie in taking EPO before the Tour of California one year.

[6] In an ESPN interview that day, Landis steadfastly denied that he had used synthetic testosterone during the 2006 Tour de France, but admitted to using human growth hormone and other doping modalities.

Landis admitted that he had no physical evidence to support his allegations of others' involvement in doping, but that his emails were intended to clear his mind.

[54] Olympic medalist Steve Hegg said he felt "betrayed" and "deceived" and characterized Landis as "a bitter guy.

"[55] David Millar, who served a two-year suspension for EPO doping from 2004 to 2006 and is on the Garmin–Transitions team, said: "If [Landis] had stood up and manned up four years ago, he'd be racing the Tour de France now.

In February 2013, the United States Department of Justice joined the whistleblower lawsuit, which also accused former USPS team director Johan Bruyneel and Tailwind Sports, the firm that managed the USPS team, of defrauding the U.S.[59][60] In February 2017, the court determined that the federal government's US$100 million civil lawsuit against Armstrong, started by Landis, would proceed to trial.

[62] In July 2011, Landis gave an interview to Graham Bensinger in which he described his plans and training to race professionally in NASCAR.

[63] In November 2011, Landis and his former coach, Arnie Baker, were convicted of "benefiting from" hacking into the computers of the Chatenay-Malabry anti-doping lab.

[64] In April 2012, it was revealed that Landis was under investigation by federal prosecutors in connection with possible wire and mail fraud committed when he raised his legal defense fund in 2007.

[67] Landis is portrayed by American actor Jesse Plemons in the 2015 film The Program, directed by Stephen Frears and starring Ben Foster as Lance Armstrong and Chris O'Dowd as David Walsh.

[70] In October 2018, Landis announced that he would launch a new UCI Continental cycling team sponsored by his cannabis business.

He indicated that funding for the team would come from the bulk of the money he received from the settlement of the Lance Armstrong whistleblower lawsuit, and that it would be managed by Gord Fraser.