The Meatworkers Union say a Court of Appeal ruling is a landmark case for unionised workers.

The Court of Appeal has thrown out AFFCO's challenge against a November Employment Court ruling that found the company locked workers out unlawfully.

The union said the judgement of the two courts is a major step forward in protecting the workers' collective bargaining rights.

National Secretary Graham Cooke said it's the first time a company has locked meat workers out from their place of work while collective bargaining is in process.

He said AFFCO intentionally laid workers off at the end of last season so it could force them to negotiate individually, without the support of the union.

AFFCO should have done what every other company does in the industry - offer a restart which would have kept them on a collective agreement, he said.

Mr Cooke said the way the company tried to manipulate workers into an individual negotiation process is disturbing.

"This company has been trying to deal with workers one on one and bypass the union in every way possible.

"They used every trick in the book and thought they'd get away with it."

Mr Cooke is questioning the business ethics of the company - they've had many more issues since Talley's bought it in 2010.

But this time he said the workers won, and union members and their families are very happy both courts ruled in their favour.

"We're talking about not only the meat workers in the North Island, but their families as well, they've gone through hell and back."