The administration's "zero tolerance" policy resulted in thousands of immigrant children being separated from their parents at the border.

A Mission Police Dept. officer (L), and a U.S. Border Patrol agent watch over a group of Central American asylum seekers before taking them into custody on June 12, 2018 near McAllen, Texas. Local police officers often coordinate with Border Patrol agents in the apprehension of undocumented immigrants near the border. The immigrant families were then sent to a U.S. Customs and Border Protection (CBP) processing center for possible separation. U.S. border authorities are executing the Trump administration's 'zero tolerance' policy towards undocumented immigrants. U.S. Attorney General Jeff Sessions also said that domestic and gang violence in immigrants' country of origin would no longer qualify them for political asylum status. John Moore/Getty Images

In May 2018, Attorney General Jeff Sessions rolled out a "zero tolerance" policy to prosecute all adults who crossed the border illegally with children, departing from the practice of previous administrations which only prosecuted parents accused of other crimes.

While adults were jailed and prosecuted for misdemeanor illegal entry, their children were placed in shelters run by the Office of Refugee Resettlement and put into a completely separate process.

The policy resulted in months of chaos and confusion at the border, as the Department of Homeland Security found themselves with no coherent plan to reunite families despite orders to do so from federal judges.

Hundreds of parents were deported back to their home countries without their children, many of whom remained in shelters, were placed with foster families, or even adopted out. The separations were denounced as cruel by politicians on both sides of the aisle, every living former First Lady, and the United Nations.