The NSW corruption watchdog has urged MPs to strengthen their code of conduct after making adverse findings against former premier Gladys Berejiklian.
The Independent Commission Against Corruption on Thursday found Ms Berejiklian acted corruptly while in a five-year relationship with a fellow Liberal MP.
A 688-page report found she had breached the public trust by failing to disclose her personal relationship with Daryl Maguire when she was treasurer and later premier.
That included sitting on a cabinet committee as it dealt with multi-million-dollar funding arrangements concerning projects enthusiastically pushed by Maguire to benefit his Wagga Wagga electorate.
The report made 18 recommendations seeking to address "systemic weaknesses" in the ministerial code of conduct, including explicitly addressing side hustles that formed the basis of the damning findings against Maguire.
"The ultimate goal is to improve and enhance the reputation of the NSW parliamentary system to the betterment of the people of the state," it read.
The commission has urged the NSW parliament to develop a comprehensive set of principles of conduct and descriptors to guide decision-making based on the values of public trust, public interest and public duty.
This requires "detailed guidelines and clear processes to assist them to navigate ethical challenges involving conflicts of interest".
Griffith University public policy and law professor A J Brown said improper and unlawful conduct by MPs is a particular problem in NSW.
"The extent of the greyness of the principles and rules of parliamentarians having outside business and personal interests, giving rise to conflicts of interest, goes to the heart of this (Berejiklian) case," he told AAP.
"In NSW, it has been regarded as acceptable."
Ms Berejiklian gave evidence to the inquiry she had believed she was not required to follow the ministerial code of conduct because a premier is not a minister.
Prof Brown said while Maguire had "no sense" of any boundary between holding office and his own personal interest, there were legitimate businesses MPs engaged with that compromised their ability to perform as elected officials.
The Transparency International Australia board member said there must be the presumption that this is unacceptable, and MPs who are moonlighting or hold secondary employment must have a very good reason to do so.
"Too many parliamentarians don't understand there is a dividing line once you take on the role."
Ms Berejiklian said she worked her hardest in the public interest while in office.
"Nothing in this report demonstrates otherwise," she said in a statement.
