The Immigration Act 1987 
Makes it an offence for an Employer, or a person acting on behalf of an Employer, to knowingly employ a person who requires, but does not have, a work permit/visa, therefore, an Employer, or a person acting on behalf of an Employer, must decline to employ anyone known to be an overstayer or without a work permit/visa, and must dismiss the Employee if such knowledge later comes to hand.
An Employer, or a person acting on behalf of an Employer who refuses to employ or who dismisses an Employee who does have a work permit/visa, cannot be in breach of the Human Rights Act 1993 as the Immigration Act 1987 states that an Employee working illegally is not legally employable in the first place.
An Employer, or a person acting on behalf of an Employer should not risk being in breach of the Human Rights Act by making subjective judgments in regards to Applicants. It would however be acceptable to have the following in all Application Forms:
If you are not a New Zealand citizen:
    • Do you have the right of permanent residency in NZ; or
    • Do you hold a current permit/visa that allows you to work in NZ
For additional protection, always ensure you obtain from the Applicant a copy of either:
    • A NZ Passport
    • A NZ Residence Permit
    • An Australian Passport
    • A Work Permit
    • A Temporary Permit

More info - www.immigration.govt.nz