In November 2011, Knauf applied to revoke Tasman's "batts" trademark and the next month, Tasman started trademark infringement proceedings.
Knauf claimed Tasman's trademark registration was not valid because the word "batts" had also become generic in New Zealand. To succeed, Knauf had to prove "batts" had become a common name in general use by New Zealanders, and that this came about by
Tasman's acts or omissions.
In his decision from May last year, the High Court's Justice Brendan Brown did not believe it had.
Even if he was wrong on this point, Justice Brown said, Knauf had fallen "significantly short" of establishing that it was the acts and inactivity of Tasman that caused the trademark to become a common name in general use.
The judge also made ruling claims from both sides that the other had breached the Fair Trading Act.
Chunks of the case went to the Court of Appeal, which today largely upheld Justice Brown's rulings.
"Our analysis of the origins of the word "batts" suggests that, at least in New Zealand, the word was not widely used or understood by the general public as a descriptive term and that it did not become a term in general public use until it began to be promoted by Tasman's predecessor after the trade mark was registered in 1973," Justices Tony Randerson, Christine French and Mark Cooper said today.
"Thereafter, in consequence of the marketing campaigns undertaken, the word "batts" became strongly associated in the public mind with Tasman's Pink Batts insulation products. We conclude that the judge was correct to find that the term "batts" had not become a common name in general public use," they said.
The Court of Appeal confirmed that Knauf's use of the word "batts" on the earthwool.co.nz website did not infringe Tasman's trademark.
However, the three judges also found that Justice Brown was right to decide that the Earthwool brand and online marketing were misleading and deceptive
The trio differed with the High Court on one aspect - on whether Knauf's use of the word "Batt" in the website's code infringed Tasman's trademark.
It is understood this was at issue because the website showed in internet searches for "batts".
While the High Court believed the use of the code did infringe the trademark, the three appeal judges said that was wrong.