National Commission on United States Counterterrorism Policy Act of 2020 This bill establishes within the legislative branch the National Commission on United States Counterterrorism Policy. The commission shall (1) review U.S. counterterrorism objectives, priorities, capabilities, policies, programs, and activities; and (2) assess how to adapt and prioritize such policies, programs, and activities to ensure that they employ a mix of available instruments of national power, comply with the rule of law and respect for civil rights and liberties and human rights, focus on terrorism risks, and are balanced relative to the pursuit of other U.S. interests. The commission shall study, among other things the evolution of threats to the United States from September 11, 2001, from international and domestic terrorism and the risks they pose relative to other threats to the United States and U.S. national interests, major lessons learned from U.S. counterterrorism activities since that date, potential new or emerging challenges, and recommendations on how best to adapt U.S. counterterrorism activities to address existing and emerging terrorism risks.