Landis, who announced his retirement on Tuesday, lost his 2006 Tour title after testing positive for testosterone and last year accused former team mate and seven-times Tour champion Lance Armstrong of doping.
He now believes the fight against doping is one that cannot be won.
"You've got to legalise doping. They (the testers) are so far behind in the testing organisations that there's no way to change it now," American Landis told Cyclingnews website (www.cyclingnews.com) on Wednesday.
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"Just accept that it's here, that it's not going away and that it's just going to get more complicated and the fact that it's not that complicated yet compared to what it will be," Landis said.
"Ten years from now it's going to be four times as hard as it is now to test for things."
The only concern should be the riders' health, added Landis, who last year accused several prominent figures in the sport of cheating.
"Since you can't stop it you have to deal with it in rational kind of way," he said.
"You can't stop it and you cant fix it. Monitor it and make sure people don't hurt themselves, but you have to accept it."
(Reporting by Julien Pretot; Editing by Ed Osmond)
