He said there had been clerical errors as in any organisation but no deceit.
Leader said most of what the Crown alleged was based on broad sweeping statements.
He reminded the jury to treat Renes as innocent until proven otherwise and to keep an open mind throughout the trial.
In his opening address to the jury, Crown prosecutor Mike Smith said there were more than 3000 claims ACC identified that were of concern.
"This was not a one-off error but a deliberate code of conduct. It wasn't whether the treatment provided was good or bad but about the method used to get the payment.
"It's not about what you're entitled to but about whether you're obeying the rules. You might think the rules are dumb, but rules are rules and they have to be complied with."
Smith said on one occasion, Renes suffered an injury and claimed earnings-related compensation from ACC while her treatment provider number was used to treat other people.
A series of claims were lodged with ACC, he said, for treatments provided by a physiotherapist on Sundays when that treatment provider never worked.
Renes took steps to try to maximise her earnings by circumventing the rules, Smith claimed.
The Crown is calling ACC staff, physiotherapists, and Renes' staff as witnesses during the trial expected to last four weeks.