"It's about ethics, integrity and honesty," he said.
Tucker said he used to work at Custom Residential and there had been issues about commission he believed he was owed, among other points of disagreement.
On March 6, 2014, the fight got dirty.
Wills' lawyer David Beard said his office received a package in a courier bag along with a letter bearing Tucker's company letterhead.
"It was opened on the steps of the Auckland Central Police Station with myself and a constable and ... I was gagging over the side, with tears in my eyes," Mr Beard said.
"I'd just been to the High Court that morning, so I was all dressed up in the black suit, the works, with haz-mat gloves."
While Tucker admitted sending the package, his lawyer Ron Mansfield said the faeces did not belong to his client.
The package was originally sent to Tucker and he believed he was returning it to the sender, Mr Mansfield said.
"So 'whose poo is it?' is a good question and why are they not charged?" he said.
Posting a noxious substance attracts a maximum penalty of a $5000 fine but Mr Beard believed it was a more serious offence.
"What's the difference between sending that and a package of smallpox? It's noxious, it hurts people, it's full of bacteria, it's harmful," the lawyer said.
"In 16 years I've never seen anything like this in my career, and I have to deal with some interesting people."
It is understood police did not have the contents of the package analysed because of health-and-safety concerns and it was subsequently destroyed.