The New Zealand Meatworkers Union's battle in Wairoa with Affco New Zealand is heading to the highest court in the land.
The Supreme Court has given Affco leave to appeal a Court of Appeal ruling that Affco unlawfully locked out union workers across its North Island plants when collective bargaining was taking place.
The Supreme Court appeal is based on whether the Court of Appeal was correct in finding a breach of the Employment Relations Act (ERA) had occurred when Affco required seasonal workers to enter into new individual employment agreements before commencing work for the 2015/2016 season.
The Court of Appeal upheld an Employment Court decision that the lockout was unlawful.
"It is obvious that Affco's objective was to undermine or compromise the parallel process of negotiating a collective agreement which was then under way with the union," the Court of Appeal said.
"The company's purpose was to fragment the future bargaining strength of the workforce by isolating individual workers.
"By this means, it took advantage of the inherent inequality of its relationship with the seasonal workers who were members of its captive workforce and to whom it owed existing duties to offer re-employment."
Lockout provisions protected former employees "who have contractual rights to an offer of re-employment".
Affco was the first employer to end bargaining under 2015 amendments to the ERA, which let firms opt out of multi-employer agreements and removed the duty, under good faith bargaining, for both sides to reach agreement.
The Wairoa dispute started in 2013 when a collective contract expired and negotiations broke down after Affco wished to change terms and conditions.
In 2015 Wairoa workers who refused to return on individual contracts were locked out for five months.
The Employment Court ordered the union members' return to work, but on their return their terms and conditions were changed markedly.
After a compliance notice was issued they were employed according to their collective agreement.
The majority of legal clashes have been at Affco's eight North Island meatworks but this week the Employment Relations Authority released a determination saying a Meatworkers Union official at Affco Hawke's Bay Hide Processors in Napier was unfairly dismissed for incidents that included swearing.
It ordered reinstatement, reimbursement of lost wages and $6000 compensation for humiliation, loss of dignity and injury to feelings.