Daniel McGowan served seven years in federal prison for his involvement with the Oregon cell of the Earth Liberation Front (ELF), an international underground movement dedicated to protecting the environment. For years, the ELF destroyed millions of dollars of property belonging to individuals and corporations that in its view profited from the destruction of the planet. What makes people turn from nonviolent disobedience to more aggressive forms of protest? As the filmmaker notes, “In one night they accomplished what years of letter writing and picketing were unable to do.” By combining astonishing archival footage of clashes between protestors and police and illuminating interviews with participants on both sides, If a Tree Falls raises questions about our definitions of terrorism as it traces the dramatic history of the ELF’s most active American cell and the path of one frustrated activist emboldened to take more extreme measures.  RM