Paddy Hill, one of the Birmingham Six wrongfully convicted of the pub bombings, said he was "very pleased" with the coroner's decision.
"This is the first step that has been taken to find out the real truth and the massive cover up [between] the judiciary, the government and Birmingham police over the last 41 years," he said outside Council House in Solihull.
But he said he was still "sceptical" that the truth will emerge before going on to repeatedly attack West Midlands Police.
"Birmingham police couldn’t spell the word truth. They’re rotten.”
Asked if his faith in the authorities had been restored by the decision, Hill replied: "No way, no way - the system has got worse."
A coroner has ruled that an inquest into the Birmingham pub bombings can be resumed.
"How dare he make such horrendous statements over the airwaves."
On Wednesday, a coroner will decide whether to open a full inquest into the 1974 Birmingham pub bombings which killed 21 people.