Greenpeace USA headed to court in North Dakota on Monday, as a trial expected to last about five weeks begins over protests at the construction site of Energy Transfer's (NYSE:ET) Dakota Access Pipeline that delayed the $3.

An attorney for Energy Transfer claimed it was "a day of reckoning," while Greenpeace attorneys said there was no evidence to prove the pipeline owner's claims.

A behemoth defamation lawsuit brought by the developer of the Dakota Access Pipeline against Greenpeace began its trial in a Mandan courtroom on Monday. Energy Transfer, a Texas-based oil and gas company, accuses Greenpeace of using underhanded means to back demonstrations against the pipeline in 2016 and 2017.