WADA plans to double the standard penalty from two years to four in the next edition of its global anti-doping code. It must be approved next year and wouldn't take effect until 2015.
WADA President John Fahey says there is "an overwhelming amount of support for the sanction to be strengthened" for use of steroids, human growth hormone and other serious doping substances.
Some athletes and sports bodies have previously challenged four-year bans in court as too severe and a restraint of trade.
But Fahey says WADA took legal advice on the issue and he's "confident the four years won't breach any current law in any part of the world."