From the introduction to The Trump Administration’s “Zero Tolerance” Immigration Enforcement Policy (R45266, Feb. 26, 2019):
This report briefly reviews the statutory authority for prosecuting persons who enter the United States illegally between U.S. ports of entry, and the policies and procedures for processing apprehended illegal border entrants and any accompanying children. It explains enforcement policies under past Administrations and then discusses the Trump Administration’s zero tolerance policy on illegal border crossers and the attendant family separations. The report concludes by presenting varied policy perspectives on the zero tolerance policy and briefly reviews recent related congressional activity. An Appendix examines recent trends in the apprehension of family units at the U.S. Southwest border.