A small number of officers throughout Scotland were given a standing authority to carry guns following the merger of the old eight forces.
Opposition parties insist this amounts to a change in the culture of policing and should have been debated in parliament.
Kenny MacAskill said it was simply a nationwide roll-out of a policy that was “endorsed” by three legacy forces - Strathclyde, Tayside and Northern.
But he was unable to say whether this policy had received prior approval by councillors on the old police boards, and said it is not his responsibility to find out.
Glasgow Labour MSP Patricia Ferguson said he must explain whether police boards had endorsed the policy.
But Mr MacAskill said it is up to the councillors who served on the old police boards, chiefly the Labour councillors on the former Strathclyde Police board, to say whether they endorsed armed officers prior to April 2013.
Mr MacAskill said: “The current standing firearms authority is not new. Three of the former constabularies - Strathclyde, Tayside and indeed Northern - had endorsed this position prior to the inception of the service.”
Ms Ferguson said: “The Cabinet Secretary has been at great pains to say that three of the former constabularies had endorsed the position of their being a standing firearms authority prior to the inception of the new service.
“I wonder if he can confirm that the police boards in these areas were of that view and gave that authorisation to the chief constable to bring about that change in policy?”
Mr MacAskill said: “I don’t think I can be asked to answer for something that is not my responsibility.
“These were the procedures carried out by those authorities. They signed them off. I think if Ms Ferguson has cause for concern she should raise it with those members who served upon that.”
Labour MSP Ken Macintosh, whose Eastwood constituency was also policed by Strathclyde, criticised the Justice Secretary’s “inability to point to any public discussion by any police board of this radical change of policy”.
Mr MacAskill said: “The decision was taken by the chief constable of Strathclyde who was held to account by the police board for Strathclyde.
“If Mr Macintosh was not aware when Strathclyde took that, it may be matters that he would wish to raise with political colleagues in his own area.”
Independent MSP John Finnie, an ex-policeman and former SNP MSP, said: “It’s inconceivable that a risk assessment would change at midnight for five of the constituent forces.
“Indeed that is lazy management. I wonder if the Cabinet Secretary will agree to publish the decision making behind that change policy for each of the constituent forces.”
Mr MacAskill said: “I don’t have that information. The information that would apply to previous police boards belongs to police boards or indeed to their constituent members.
“It’s not something that the Government would routinely have access to. That is an issue that the member would be perhaps better raising with council colleagues.”
SNP MSP Kevin Stewart, a former member of Grampian police board, said: “Having served on a police board for some 13 years, I can say wholeheartedly that with the local policing committees, the Scottish Police Authorities and the policing sub-committee we now have greater scrutiny than we have ever had before.”