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.

Opponents of the Dakota Access Pipeline demonstrate in Bismarck in August 2016. (Kyle Martin/For the North Dakota Monitor)BISMARCK, N.D. (North Dakota Monitor) — A behemoth defamation lawsuit brought by the developer of the Dakota Access Pipeline against Greenpeace began its trial in a Mandan courtroom on Monday.

The trial in North Dakota that observers are describing as a key free speech rights case has begun. Energy Transfer, a Texas-based company and the operator of the Dakota Access Pipeline, is suing Greenpeace for alleged defamation and what their lawyers describe as a “campaign of violence.”