The complaint was first upheld in April this year, however Kirkwood asked for an appeal on the grounds that she was not notified of the complaint so could not make a submission.
In her submission last month, Kirkwood said it was incorrect to interpret evidence provided by the council as proof that the posters had caused serious or widespread offence.
"There was no evidence of any complaints from the public. There was no evidence of any member of the public being seriously offended or of many members of the public being offended on any level."
Kirkwood went on to provide a dictionary definition of 'offence'.
"Content which is provocative because it is dramatic, confrontational and upsetting is not always offensive," wrote Kirkwood.
She said the signs aimed to stimulate debate, portray a social message and educate.
A majority of the board agreed the posters were offensive as their placement meant they were visible to pedestrians including children.
However the images were believed to be of such poor quality that some members of the board struggled to identify whether or not they were capable of causing offence.
The posters were also classified as 'advocacy advertising' by the board, as they contained images of animal cruelty in a public place. The identity of the advertiser, Kirkwood, was also not clear - a requirement of ASA's Code of Ethics.
In a letter to the Council earlier this year, Kirkwood said the posters were a protest, not advertising.
"It is the practice of vivisectors and other animal abusers to hide their crimes.
"I am trying to expose it. I insist on my rights. If we do not protest animal abuse we condone it.
"There are worse sites online, on TV and in supermarkets and butchers."
