The Greens' Shane Rattenbury tabled new freedom of information legislation on Thursday, after months of negotiation and about 60 drafts.
Mr Rattenbury said the bill would take the ACT "from being one of the least open FOI jurisdictions in the country to being one of the best".
But he has had to compromise on Cabinet papers, which Mr Rattenbury had wanted treated like any other government document, but which will be given a special exemption.
The bill requires government departments to publish incoming-minister briefs, question-time briefs, and estimates and annual reports briefs three years after they're written, unless publishing is against the public interest. Ministers' diaries must also be published and "must include all the appointments and meetings that relate to the minister's ministerial responsibilities".
Each agency must appoint an "information officer" to make decisions about access to government information, and instead of being done internally, reviews will be done by the ACT ombudsman.
The ombudsman will also investigate complaints and publish guidelines on the scheme.
The bill creates a right to information unless its release is contrary to the public interest. When applying the public interest test, an agency is not allowed to take into account issues such as embarrassment or loss of confidence in the government, the possibility of creating confusion or unnecessary debate, or the reasons the information has been requested.
But there are a number of reasons information can be withheld because of "public interest", including information created for Cabinet, Cabinet notebooks and notes. But triple bottom line assessments done for Cabinet will be treated like other government information.
Agencies can withhold information whose release could "prejudice the security or good order of a correctional centre", "prejudice the economy of the territory", and prejudice the "business affairs of an agency or person" or the "competitive commercial activities of an agency", as well as information relating to terrorism or from national security agencies.
The bill says information officers should start from a presumption of releasing information and needing to be positively convinced that it is contrary to the public interest to release it. If the decision is line-ball, discretion must be in favour of disclosure.
With some FOI requests attracting bills amounting to $10,000, the new bill says agencies must not charge for the time it takes them to process an application, but they can charge for the amount of information released. The first 50 pages must be free, and fees should be waived for not-for-profit groups and concession card holders.
The bill makes it an offence to prevent the disclosure of information – through, for example, destroying information or not recording information that should be recorded, or using removable post-it notes rather than annotating a document.
It authorises agencies to provide information requested informally, without forcing people to go through a formal FOI process.
The bill, agreed in the Greens and Labor power-sharing agreement after the 2012 election, is modelled on the Queensland 2009 laws which have a public interest test and are based on the "push" principle of public information, which Mr Rattenbury described as the country's most progressive. He hopes to have the bill debated in June or early August.
"It's been challenging because it's such a big shift. It's taken quite some discussion to get this far," he said, with the Bill having already been through 60 drafts and the possibility that Labor or Liberal will try to amend it further in debate.
"This is a significant change in approach to how freedom of information is dealt with in the ACT. It's designed to drive a culture change that requires the release of information, rather than a requirement to ask for it."
Mr Rattenbury said currently the government decided what information to release, creating an obvious conflict of interest.
"Access to government information should be based on the best interests of the community and not the interests of the individuals or party forming the government of the day."