James Hird says his trust was broken and that's why he broke his promise to create a safe environment for his players at Essendon.
The former Bombers coach also said the AFL put "spin" first and fairness last during the ASADA investigation into the club's 2012 supplements program.
The Court of Arbitration for Sport this week upheld the World Anti-Doping Agency's appeal against the AFL tribunal decision to clear 34 past and present Essendon players of taking the banned substance thymosin-beta 4 while Hird was coach
The decision meant those players have been banned from the sport for 12 months.
In a column published by the Herald Sun, Hird said he would have demanded an explanation from his coach if he had been exposed to similar circumstances as a player.
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"My explanation to the players is that my own trust was broken," he wrote in the Herald Sun on Friday night.
"As a consequence, the environment I had promised to create for the players was compromised.
"I apologise to the players and their families."
Hird said he had taken people at their word.
"If I were to do things differently, it would be to trust less, to ask more questions, and demand more answers," he said.
Hird said former AFL CEO Andrew Demetriou told former Essendon chairman David Evans about a report, which would say that Bombers players took performance-enhancing drugs.
He said the AFL was always looking for a managed outcome.
"For us, it felt like spin first and procedural fairness last," he said.
Hird said questions needed answering about the behaviour of the AFL, who were "desperate to put a high-profile head on a spike."
"Why was the AFL making decisions regarding potential sanctions 16 days before the first ASADA interview was conducted, as revealed by documents discovered in the Federal Court case?" he said.
Hird repeated his line that the 12-month bans were a miscarriage of justice.
