The question of responsibility for the effects of global warming is – slowly – being tested in court. One case in Massachusetts is using consumer laws to take on oil giant ExxonMobil. If the US state wins, it will be the first case in the world to successfully prosecute a fossil fuel company for greenwashing and misleading the public.

How much is the fossil fuel industry actually doing to tackle climate change? If you listen to the companies themselves, quite a lot. ExxonMobil, the American oil and gas giant, says it’s committed to new energy solutions that don’t contribute as much to global warming – such as fuel made from algae.

The firm claims it could “one day power planes, propel ships and fuel trucks and cut their emissions in half”. One of its adverts says: “Every technology we’re working on helps lower our carbon footprint. Because when it comes to addressing climate change, our actions make a difference.”

But not everyone’s buying it. “There’s this giant disconnect,” says Naomi Oreskes, a professor at Harvard University, who’s been monitoring disinformation tactics used by big businesses for years.

“The reality of their business model is to continue to exploit, develop and sell oil and gas. But their advertising, their communications, make it seem as if they’re these great guys committed to sustainability and renewable energy.”

It’s what ExxonMobil’s critics have described as greenwashing – pretending to be greener than you actually are. In other words, a form of alleged deception. And – partly because of that – Exxon and other oil companies are fighting various forms of legal action across the US.

The state of Massachusetts is taking on Exxon in court using consumer protection laws alleging the company continues to deceive the state’s consumers and investors about the damage caused by its oil and gasoline products. Exxon strongly denies the allegations.

The company has tried – and failed – to get the whole case dismissed on the grounds that many of the allegations made in this case fall outside the jurisdiction of Massachusetts courts, and the ads were not made in or specifically directed at residents in the state.

But it’s partly because of what climate change is doing to the people of Massachusetts that the state decided to take Exxon to court. Among other things, specifically mentions the threat against fishermen, and their way of life.