Rule 45 - or the Osaka Rule - was removed amid fears that such a rule could be challenged legally after the United States Olympic Committee (USOC) successfully argued on behalf of Beijing 2008 400 metres champion LaShawn Merritt at the Court of Arbitration for Sport (CAS) that it was unfair because it was a second punishment for the same offence.
There are fears that a four-year doping ban will face similar legal challenges for being too harsh but Fahey feels that WADA will be successful in implementing the ban.
"Whenever we look at strengthening sanctions for doping offences, we need to take in to account the principle of reasonability and human rights," he said.
"We have taken legal advice over this issue and we are confident the four years won't breach any current law in any part of the world.
"This is really about creating a harmonised approach and there was an overwhelming amount of support for the sanction to be strengthened.
"The Code review is intended to increase the effectiveness of anti-doping, and athletes must know that there is a heavy price to pay for intentional doping, that the risks are high.
"This is still a draft and it can be challenged until March 1 but I am confident that our own stakeholders will back it."
Legal challenges became commonplace for the International Association of Athletics Federations (IAAF) when they had a four-year ban in place in the 1990s and they lost the majority of their court battles as their ruling was consider overly harsh under European law.
The most high-profile case involved the German sprinter Katrin Krabbe, the 100 and 200 metres world champion in 1991, who was suspended for four years for taking the banned drug clenbuterol in 1992, but successfully sued the IAAF in a Munich Civil Court.
They found her penalty unlawful, effectively restricting the German Athletics Federation to two-year bans for drug use.
Krabbe's move, and other successful legal challenges in other European countries, forced the IAAF to drop four-year bans to avoid potentially huge legal bills.
Expensive legal battles would be a real problem for WADA because their funding has been frozen for a second successive year at approximately $28 million (£17.5 million/€21.8 million) due to the continuing worldwide economic crisis.
"This is the second year in a row that we have received a zero-per cent increase, and while we appreciate that economies across the world continue to struggle, this freeze is not ideal for the fight against doping in sport," said Fahey.
"It is widely accepted that doping is a major issue no longer restricted to the sporting world and that it must be addressed by society as a whole.
"WADA has dipped into reserves over the last two years to cover shortfalls for its operating costs.
"But if funding continues to remain the same then the WADA will be forced to cut back its activities."
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