At a June 25 Strategy, Policy and Finance committee hearing on the sewerage proposal, Williams said the legal advice had found it was unlikely a court would accept Macpherson could both come to a final view as a private citizen and also remain open to persuasion as an elected councillor.
In the council chamber on June 30 the Strategy, Policy and Finance committee made the step of formally requesting Macpherson step down from annual plan deliberations - he refused.
On Thursday, Williams told the Rotorua Daily Post it was important to seek advice to try to mitigate the risk predetermination could cause the council.
"Councillor Macpherson also requested that the organisation seek legal advice about this."
He said the "worst-case scenario" would be an affected party challenging a council decision through judicial review.
"There would be significant implications if that happened, including legal costs, loss of public confidence and the cost and time that would be involved in having to repeat consultation and/or decision-making if that were required as a result.
"It is absolutely critical, in guarding against these risks and to ensure we operate in an efficient and effective manner, that [the] council applies best decision-making practice."
He said the invoice for legal advice into predetermination to date had come to $10,031.70.
"[The council has] not yet been invoiced for the remainder, including counsel coming to speak to our elected members [on June 30]. We estimate that the total will come to about $20,000.
"It's fair to say that dealing with work like this diverts from other tasks. Staff time has probably totalled about 20 hours on this particular matter."
On Friday, Macpherson confirmed he had requested the council seek legal advice on the issue.
Macpherson said in his opinion, Williams had offered up political advice to [the] council that had whipped up unwarranted fears about judicial reviews, encouraging elected representatives to allege bias and predetermination to suppress criticism of the draft annual plan.
"[I] believe that it was political advice intended to suppress our criticism of the draft Annual Plan."
Despite Macpherson also requesting the council seek legal advice, he said, in his view, the responsibility for "running up these legal costs" lay "solely with the chief executive".
"There are no legal risks to elected representatives making submissions on public policy issues, especially if they are presented as preliminary positions.
"All I did was ignore an internal political norm that, in my view, gives officials undue influence over the policymaking process.
"I will not be seeking their permission on when and how I will exercise my right to freedom of expression."
Macpherson also took aim at Strategy, Policy and Finance committee chairwoman Merepeka Raukawa-Tait, saying, in his opinion, she had "exceeded her authority" when she moved a motion formally requesting Macpherson step down from deliberations on the annual plan.
Acting chief executive Craig Tiriana said a key role of the chief executive was to advise and support elected members to enable effective decision-making and good governance.
"Legal advice was requested and was provided. Tompkins Wake is a reputable law firm and is [the] council's legal advisor."
In a written statement via the council communications team, mayor Steve Chadwick said: "The time and place to debate things is in the chamber. What I'm focused on is doing what needs to be done for our community.
"We have set a direction and have a recovery plan and it's disappointing that yet again, rather than the media reporting on that, we are instead discussing process because someone didn't get their way."
She said in her opinion it was "a bit rich for Councillor Macpherson to be critical about legal advice and costs resulting from his own unwillingness to follow proper process or take advice".
She said chairing meetings, "you have to call it as you see it – there's no third umpire and the chair is charged with ruling on all matters of procedure".
"It's clear Councillor Macpherson is...having difficulty with the workings of council and I encourage him to get some help with that.
"He is also welcome to get his own legal advice, rather than stooping to alleging bias because he didn't like what he heard – that is very poor form," Chadwick claimed.
At the July 2 Operations and Monitoring committee meeting Chadwick had asked chief financial officer Thomas Colle how "legal costs" regarding "governance" were impacting the council's budget.
"It is something that the community is asking me because they're reading about it all the time in the newspaper, is what is happening to our legal costs? ... Have our legal costs gone up?
"That has been something that has bothered a lot in our community.
Colle responded he would "tippy-toe" around the issue, but said it was "safe to say that our budgets are under immense pressure in a couple of areas in regards to ongoing legal costs".
On Friday Raukawa-Tait told the Rotorua Daily Post Macpherson was, in her view, "whinging again, insisting on telling everyone what they're doing wrong".
"[He] has no traction with the majority of councillors who focus on the job at hand. They are the ones who have my respect and clearly know their responsibilities as elected representatives of the people of the Rotorua Lakes district."
