Between August and November, 2017, the Myanmar military carried out a series of brutal attacks against Rohingya Muslim communities in Rakhine State in Myanmar. Myanmar’s military used Facebook as a tool for ethnic cleansing. In theory, Rohingya plaintiffs could bring a state tort law claim against Facebook alleging that Facebook was negligent (or worse) in permitting its social media platform to be utilized to spark mass violence against the Rohingya. Could Facebook be held liable in a civil suit for complicity in genocide, or for aiding and abetting the commission of a crime against humanity? Under current federal law, the answer is clearly “no.” Section 230 of Title 47 of the U.S. Code states: “No provider or user of an interactive computer service shall be treated as the publisher or speaker of any information provided by another information content provider.” Judicial decisions establish that Section 230 grants online service providers broad immunity for content posted by third parties. Thus, Section 230 provides Facebook a valid federal preemption defense to a state tort law claim. This essay contends that Congress should create a statutory exception to Section 230 to permit civil suits against social media companies for complicity in genocide or crimes against humanity. The United States has a clear duty under international law to prevent genocide. One could also make a persuasive argument that the United States has a duty under customary international law to prevent crimes against humanity. The United States is not violating its international legal duty to prevent mass atrocities by granting immunity to internet companies. However, withdrawal of that immunity for content that contributes to commission of mass atrocity crimes would be a helpful step for the United States to implement its duty to prevent genocide and crimes against humanity.