Last year wasn’t great for lawyers or environmentalists in the courts. Even though cities, counties, and one fishermen’s association filed lawsuits against major energy companies, none of the cases have gotten very far in the court system and many were thrown out entirely.

That doesn’t mean activists are taking the hint, though.

In fact, at a Thomson Reuters Foundation event held in New York City last week, a who’s who of green activists – including the Union of Concerned Scientists’s Peter Frumhoff, recent Congressional witness Jeffery Sachs, and Columbia University’s Michael Burger – made it clear that their latest approach is to double down on lawsuits, endorsing litigation as an effective means to hold fossil fuel companies accountable for climate change.

“I believe in suing everybody,” said Sachs, accusing oil companies like Chevron and ExxonMobil of lying to customers about climate change for decades. Sachs, a Columbia University professor, has taken similarly extreme positions in the past, advocating for population control and even alleging that the victims of Hurricane Harvey were responsible for the disaster.

At a House Oversight Committee hearing in early April, Sachs blasted lawmakers for “fail[ing] to adopt any major legislation” to stabilize greenhouse gas levels. He even went so far as to tell the committee that “climate safety is now nearly out of reach” and criticized members of Congress for accepting donations from oil and gas companies.

Sachs continued this anti-fossil fuel rhetoric at the Reuters event, arguing passionately for lawsuits against a wide range of companies:

“Who could you sue? You would sue the ones that are responsible. That could be the oil companies, because the big oil companies have contributed a discernable share of the increased concentration of CO2. You could sue governments, like our own…that are treaty-bound under the U.N. Convention and yet willfully, deliberately, corruptly going the opposite direction… And you can sue the banks.”

Event attribution, a controversial tactic from environmentalists, has been a key part of these cases from the start. It was discussed at the 2012 meeting in La Jolla, Calif., where the activists laid out their strategy to go after energy companies in the courts.  First attempted (unsuccessfully) in American Electric Power Co. v. Connecticut, event attribution tries to identify what percentage of an extreme weather event can be blamed on climate change and, by extension, what percentage of damages an energy company might be responsible for. (Several of the key reports used to make these determinations come from groups funded by the Rockefeller Brother’s Fund.)

For the sort of wide-ranging lawsuits Sachs proposed, event attribution analysis would be foundational, but its record in court has been mixed.

“This sort of climate science has been part and parcel of climate litigation from the beginning and it has never had a determinative effect in the outcome of a case,” said Michael Burger, executive director of the Sabin Center for Climate Change Law at Columbia University School of Law.

Burger noted that while the lawsuits filed by cities, counties, and one fishermen’s group against oil companies have been strengthened by event attribution, it hasn’t been a primary focus of the cases. In fact, he believes that legal doctrines “stand in the way” of such cases moving toward a trial.

Despite this belief, Burger is still trying to help lawyers attack energy companies in the courtroom.

The Columbia professor recently wrote several chapters in a 1,000-page legal compendium that provides a cynical playbook for eliminating fossil fuels at all levels of government. Burger also served as counsel on an amicus brief that was filed in support of the Oakland and San Francisco public nuisance suits against back in March.

Meanwhile, other environmentalists featured on the Reuters panel think it is time for the movement to change its legal strategy to pursue smaller cases against individual actors who “should have known” the impact of their actions.

Approaching the issue from the perspective of insurance law, Lindene Patton, an attorney with the Earth and Water Law Group, thinks that there is an opening for professional liability litigation against smaller actors using environmental and product liability law. The argument at the core of these cases, according to Patton, would be that individual actors have a responsibility or duty to react in a certain way in response to accepted climate science, and failure to do so would leave that party liable for negligence:

“The attribution science, from a detail perspective, informs not only what your duty of care is, but informs in a very specific common law analysis looking at negligence whether a particular damage was foreseeable or not.”

This means climate lawsuits would no longer be restricted only to fossil fuel companies. For Patton, the ability to target a broad range of actors is a benefit of the new strategy.

“If what you want to do is change behavior, and you want people to improve resilience and decrease emissions, [it might be worth stepping back]. You go to licensed professionals who have a duty and the attribution science is easier to apply there first to make a change.”

This legal theory might allow the green movement to sue more companies, but it also likely sets them up for more defeats. Litigation has so far proven to be an ineffective strategy and is one driven by politics rather than an honest effort to improve the environment. Activists and attorneys can continue to drum up additional, similarly far-fetched legal avenues in an effort to take energy companies to court, but no theory will change the fact that climate change is a policy issue that cannot be lawfully decided in the courtroom.