District health boards in Auckland say patients will not notice any change when a new operator takes over all medical testing in the region.
Lab Tests, which is owned by the pathology provider Healthscope, is to take over from Diagnostic Medlab Limited following a legal ruling.
The Court of Appeal on Thursday overturned a judicial review by the High Court in March 2007 which resulted in the contract being returned to DML over a conflict of interest and lack of consultation.
It found the earlier ruling was too broad and DHBs have the authority to make contracting decisions.
The Court of Appeal said there was no need to consult in this instance.
DHBs say that has provided much-needed clarity and service standards will be maintained during the transition.
The original contract was $560 million over eight years.
The Court of Appeal ruled Lab Tests should take the contract as soon as it can after an interim deal with Diagnostic Medlab Limited ends in December.
The court awarded costs of $48,000 each to Lab Tests and the DHBs as a group.
The Auckland District Health Board has welcomed the Court of Appeal decision.
However, DML says it will fight the decision and now has 20 working days to ask the Supreme Court to hear an appeal.
Chief executive Dr Arthur Morris says the Appeal Court has taken a narrow view of what it can review.