Global warming. Courtesy image.

The last five years have seen an influx of lawsuits filed against big business and governments over climate change and the environment.

Just Monday Connecticut joined Massachusetts and California in litigation to force the federal Environmental Protection Agency to issue rules on toxic asbestos, with changes that include a provision requiring importers to report items that contain asbestos.

But experts say it's a hard road for those bringing suit on environmental issues, a subject that divides along political, fiscal and ideological lines.

The two biggest hurdles that make it difficult to sue and win: causation and establishing legal standing, said Joseph MacDougald, executive director of the Center for Energy and the Environment at the University of Connecticut School of Law.

“You need to establish that the grounds you are suing [on] are not covered by the current environmental laws,” MacDougald said.

Shipman & Goodwin attorney Andrew Davis agrees one of the biggest potential pitfalls involves showing a direct link between government action and the alleged adverse effects at the center of the litigation.

“Causation is huge,” said Davis, who chairs the firm's environmental practice. “If you can't demonstrate causation as an attorney, you just can't win.”

A third hurdle: defense claims of sovereign immunity, according to environmental lawyer Alfred Smith Jr., a partner with Murtha Cullina.

“You need to … prove the government has an obligation to do something and failed,” he said.

Plus, powerful oil and energy companies have deep-pocketed lobbyists working on their behalf.

“Many of the environmental laws were written with significant input from the regulated industry,” Smith said.

But in court, experts say it often comes down to which side is best able to avoid the pitfall of presenting overly complicated information.

“In swaying a jury, you go to the science,” Smith said. “You need to be able to communicate to a jury in a way that nonscientific people can understand. You use facts, but you can also use metaphors that jurors can relate to.”

Meanwhile, states and municipalities are pressing ahead with litigation. New York and Massachusetts, for instance, have sued Exxon Mobil, claiming the company misled the public about the risks of climate change. And nine cities and counties from across the country have sued fossil fuel companies seeking monetary damages for climate change damages. California is also among litigants suing several oil and gas companies, and seeking billions of dollars to pay for such measures as sea walls to protect coastal properties.

Despite the uphill climb experts predict, Connecticut Attorney General William Tong is optimistic about the states' suits against the EPA, and other similar litigation involving scientific conflicts.

“Lawyers in many practices have always had to be quick studies,” Tong said. “Most people and attorneys follow developments in science and, frankly, developments in public policy.”