The Swiss-based Court of Arbitration for Sport (CAS) delivered the verdict Tuesday, confirming that the the cited players, including Bombers captain and Brownlow Medal holder Jobe Watson, would not be eligible for the next season, which kicks off in March.
Watson, who won the Brownlow honor in the season in question, may also be stripped of the medal, which is awarded to the league's best and fairest player. The case will be examined by an AFL panel next month.
The club's coach at the time, James Hird, said
the result was a "miscarriage of justice for 34 young men." He was banned for 12 months in 2013 and later resigned.
The players took supplements with the approval of the club, and may initiate legal action after being given false assurances, Australian media reports suggest
"What they did at the time is nothing short of disgraceful and you can't escape that," Australian Football League Players Association (AFLPA) chief executive Paul Marsh said. "The players are in this position because of the Essendon football club."
Of the 34, 12 are still on Essendon's books, while another five have joined other AFL teams. A further ten have been de-listed, five have retired and two more traded.
The CAS findings are at odds with an AFL anti-doping tribunal's not-guilty verdict from last year. The World Anti-Doping Agency (WADA) appealed last year's verdict and referred the case to CAS.
"This finding is heartbreaking for our players, who will struggle to understand how two tribunals could come to such different conclusions based on the same evidence," Essendon chairman Lindsay Tanner said in a statement
posted on the club's website.
He added that the "supplements program" of 2012 was a "mistake of the highest order" but that to impose bans on the players was "manifestly unfair."
The Bombers have been granted dispensation to sign ten "top-up" players to pad out the team, but the other clubs who have signed former Essendon players have not. The banned players can train, but not in any formal club setting or with club coaches.