Most Australians would find "darkly humorous" a campaign pitting energy giant AGL's logo next to the tagline "Australia's greatest liability", a judge says.
But Greenpeace will have to stick to satire after the Federal Court on Tuesday ruled some social media posts using the logo lacked parody and therefore breached AGL's copyright.
Greenpeace launched a campaign in May that used the AGL logo alongside the tagline and a report detailing the energy giant's responsibility for eight per cent of Australia's carbon emissions.
The environmental organisation also produced a report on AGL's activities, accusing the company of falsely presenting itself as a climate leader.
AGL sought an urgent injunction in the Federal Court, saying allegations of environmental wrongdoing were "unsubstantiated" and it wanted to protect its copyright.
It didn't want to suppress public debate on climate change, it said.
But the campaign involved the "wholesale reproduction of the logo" and could not be considered satirical, John Hennessy SC told the court last week.
Greenpeace argued its use of the AGL logo should fall under "fair dealing" provisions in Australian copyright law as it is clearly satire or parody.
Justice Stephen Burley agreed with the not-for-profit on Tuesday.
Greenpeace's use of the logo was immediately juxtaposed by a play on the company's initials and words decrying its environmental practices, the judge said.
Having a corporate look and "an obviously non-corporate message (created) an incongruity that is striking to the viewer".
"The ridicule potent in the message is likely to be immediately perceived,' he said.
"Many would see these uses of the modified AGL logo as darkly humorous because the combined effect is ridiculous. AGL is exposed to ridicule by the use of its corporate imagery including by use of the modified AGL logo to convey a message that AGL would not wish to send."
The words "Presented by Greenpeace" were also positioned closely, leaving the reader in no doubt who authored the message.
The judge also deemed a poster shaped like a black cloud and held over AGL's Loy Yang A power station as providing "a humourous juxtaposition".
However, no satire was featured in a photo of a school student holding a poster that contained only the logo, the term "Australia's Biggest Climate Polluter" and "Greenpeace".
That, and a handful of other social media posts and placards, did breach AGL's copyright, Justice Burley ruled.
AGL also ran a trademark infringement claim, which failed as the court ruled Greenpeace was not promoting any goods or services with the logo.
Greenpeace said the ruling was an affirmation that the law "is on the side of freedom of expression", promising to continue pressuring AGL to close its coal-burning power stations by 2030.
The energy giant welcomed the court's ruling that its logo had been misused on some occasions and reiterated the case was about "the integrity of how our brand is used."
"AGL understands its role as Australia's largest integrated energy generator to lead the energy transition while continuing to deliver reliable and affordable energy," a spokeswoman said.
The parties will return to court on Thursday to address questions of costs and the form of injunctive relief.