The oil giant BP has again failed in its long-running bid to trademark the colour green in Australia.



The intellectual property watchdog, IP Australia, found BP was unable to show “convincing evidence” that it was indelibly linked in the average petrol consumer’s mind to the dark green shade known as Pantone 348C, a spokeswoman for the government agency said.



BP first tried to register a trademark for the colour in 1991, and until 2013 fought legal battles against another corporate titan, Woolworths, to stake its claim to the colour as the dominant shade for its service stations.



A spokeswoman for the energy company did not confirm whether BP would continue trying to claim the colour, saying only: “The colour green has been central to the BP brand since the 1930s and we believe it should be protected.”



Colours, like sounds and smells, are particularly hard to trademark, because a company needs to prove the shade sufficiently distinguishes its brand from others.



Some companies have succeeded. The Queensland fruit grower Fada has claimed the red wax that covers the bottom third of its bananas. The American jeweller Tiffany has a trademark in some jurisdictions on its traditional blue hue, while in Australia the pet-food brand Whiskas has won the right to the colour purple.



But even then, says Bruce Arnold, a University of Canberra law professor specialising in IP law, the trademark applies only narrowly.



“People sometimes think that someone is going to actually own a particular colour, but it’s not as simple as that,” he said. “It’s a particular shade of colour that the rights holder owns, which they only use to identify their goods and services.



“So if BP had got green, it could have claimed that shade in relation to their products, but I could still wear a green jumper or a green tie.”



BP’s most recent claim on the colour extended to fuel, car service stations and take-away food services.



Arnold said courts were more likely to grant a colour trademark if doing so would minimise or prevent consumer confusion. He gave the example of Cadbury, which recently won a trademark on the colour purple in the UK, on the grounds that customers angling for a fix of the company’s chocolate were likely to grab for any purple-wrapped confectionery product.



But these confusion claims have been harder to prove in Australia. In 2011 the hardware chain Mitre 10 sought an injunction against a newcomer to the market, Masters, whose white lettering on blue background, Mitre 10 said, would trick consumers into thinking the stores were affiliated, or the same.



The injunction was denied, the judge reasoning that white and blue were standard colours for hardware brands, that Mitre 10 had been using the colours only since 2007, and that, “in the face of clearly different names and marks labelling the rival stores”, no customer was likely to confuse the two.



“When colour trademarks were first introduced in Australia, there was speculation we’d have major problems,” Arnold said. “There was speculation that law firms would be pushing colour trademarks to a range of businesses, and we’d see a wave of trademark registration.



“But that hasn’t happened. Basically, colour trademarks look like a bit of a fizzer,” he said.

