Strategic lawsuits against public participation, or SLAPP suits, are civil claims brought against people or organizations who voice opinions publicly. These lawsuits are intended to intimidate opponents and suppress advocacy efforts by forcing critics to spend time and money on expensive litigation.

The term “SLAPP suit” was coined by law professor George W. Pring and sociologist Penelope Canan in their 1996 book “SLAPPS: Getting Sued for Speaking Out.” The authors provided examples of SLAPPs filed in response to advocacy on many issues, including civil rights, environmental preservation, consumer protection and women’s rights.

SLAPP suits often exploit power and financial imbalances. Responding to lawsuits is expensive. Lawyers are pricey, and so are court costs and litigation expenses, such as collecting evidence, interviewing potential witnesses and purchasing specialized software to manage electronic data.

Lawsuits also are mentally and emotionally taxing. Requirements such as disclosing documents, making court appearances and being subject to questioning can make heavy demands on participants’ time and attention. Litigation can last for years.

These burdens, or even the prospect of them, can have a chilling effect on free speech.

Conflicts between developers and environmental activists are ripe for SLAPP suits, sometimes labeled eco-SLAPPs. For example, a civil trial began in North Dakota on Feb. 26, 2025, in which Energy Transfer, a Texas company that builds pipelines, is suing the environmental organizations Greenpeace USA and Greenpeace International.

Greenpeace was involved in protests in 2016 and 2017 against construction of the Dakota Access pipeline, which connects oil production areas in North Dakota to energy markets in Illinois. Along with other advocacy groups and Native American tribes, Greenpeace opposed plans for the pipeline to cross the Missouri River upstream of the Standing Rock Sioux Tribe’s reservation. Protesters argued that this design threatened tribal water supplies if the pipeline should spill or leak.

The Obama administration blocked the disputed section of the pipeline in 2016, but the Trump administration approved it in 2017. The pipeline was completed and entered operation in that year, despite large-scale protests.

Energy Transfer is suing Greenpeace for damages that the company says it incurred because of construction delays on the pipeline. The company argues that protests and demonstrations organized by Greenpeace caused these delays.

Along with claims of trespass and nuisance, Energy Transfer alleges that Greenpeace defamed the company to its financial backers. The company says that Greenpeace included false statements in a letter to the company’s banks that asserted construction of the pipeline desecrated tribal burial grounds and important cultural sites.

As a result, Energy Transfer claims that it lost US$68 million in financing and was forced to spend millions of dollars on public relations efforts to remedy the damage. The company is seeking monetary damages in an amount to be proved at trial.

Greenpeace contends that the lawsuit is an attempt to silence its free speech and protest rights, and that the letter sent to banks was an act of free expression providing information already cited many times by tribes opposing the pipeline.

Unlike many other states, North Dakota does not have an anti-SLAPP law. Currently, 35 states and Washington have laws designed to reduce the harms caused by SLAPP suits.

These statutes vary greatly, including with regard to the types of speech they protect. Some laws seek to blunt the economic harm of SLAPP suits and require litigants who bring SLAPP suits to pay defendants’ legal costs and attorney fees if those suits are unsuccessful. Other statutes merely permit such shifts at the judge’s discretion. These variations mean that cases may fare very differently based on where a lawsuit is filed.

Greenpeace leaders say a verdict ordering the organization to pay hundreds of millions of dollars in damages could drive the group into bankruptcy. Such an outcome would have an obvious chilling effect on other environmental groups – the kind of result that anti-SLAPP laws are designed to prevent.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Jennifer Safstrom, Vanderbilt University and Ryan Riedmueller, Vanderbilt University

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The Vanderbilt First Amendment Clinic receives funding from the Stanton Foundation to litigate cases related to speech, press, assembly, and petition rights.

Jennifer Safstrom has served as counsel on the following cases raising SLAPP/anti-SLAPP issues: Tayloe v. C-Ville Holdings, Goldman v. Reddington, and Tate v. Doe.

Ryan Riedmueller assisted with representation raising SLAPP/anti-SLAPP issues in Tate v. Doe.