But a copy of the code of conduct of INZ's parent organisation, the Ministry of Business, Innovation and Employment, which applies to immigration officers, shows some of the comments Casson made on social media may have breached its rules.
The six-page document outlines a raft of expectations of all its employees, whether they be full, part-time or contractors, including ensuring that personal views do not discredit MBIE or jeopardise its relationship with clients and/or the minister.
Staff are also expected to make sure "any communications they make, whether internally or externally, are professional and respectful" and be mindful of backgrounds, differences and perspectives of who they work with and serve.
The code continues that employees' actions must withstand public, legal and parliamentary scrutiny and enhance MBIE's reputation.
"We are inclusive, respectful and responsive in our dealings with all people regardless of their position, personal characteristics or situation," the document said.
"We can make sure our actions can withstand public, legal and parliamentary scrutiny and will enhance MBIE's reputation."
University of Auckland law professor Bill Hodge said Casson's comments regarding refugees, albeit it in his personal time, could be seen as bringing the organisation into disrepute and a form of misconduct.
He said Casson's earlier comments calling refugees scum was "contrary to INZ's Raison d'etre to operate a policy for the benefit of New Zealand and to adhere to international commitments".
"An employee's comments privately on his Facebook page, on some Twitter feed, on some other social media can definitely be seen as a form of misconduct related to his employment relationship, related to his employer to the extent that it could bring the employer into disrepute.
"... Language like that and remarks like that could be seen as 'wow, is that the attitude of New Zealand Immigration'. Well that's not a very good stance or a position that is tolerable."
Hodge said there had been a similar case where an employee for Child Youth and Family was fired after he was seen hitting his child across the face with his open hand at a squash court because it was found to be contrary to the organisation's image as protecting young people.
MBIE's code of conduct, according to the document, applies to all its employees and states that any breaches of the code of conduct will be subject ot an investigation and could result in disciplinary action.
The action could include a first formal warning, a final warning or dismissal either with or without notice.
As of Tuesday night, Hamilton City Council had received eight formal complaints or enquiries about how to lay a complaint about Casson. Council chief executive Richard Briggs said yesterday he had not been found to have breached the council's code of conduct.
