Congress has repeatedly granted the executive branch broad power in enforcing immigration laws. The 2002 law creating the Department of Homeland Security explicitly said the executive should set “national immigration enforcement policies and priorities.” The Supreme Court has recognized the leeway Congress gives the executive branch in deportations. In a 2012 majority opinion written by Justice Anthony M. Kennedy and joined by Chief Justice John G. Roberts Jr., the court noted that “a principal feature of the removal system is the broad discretion exercised by immigration officials,” including the decision “whether it makes sense to pursue removal at all.”

Setting enforcement priorities is vital to the effectiveness of our immigration laws. Congress can’t anticipate every situation. This is why the Supreme Court recognized in 1950 that immigration law is an area where “flexibility and the adaptation of the congressional policy to infinitely variable conditions constitute the essence of the program.”

The immense moral and legal consequences of a deportation campaign targeting up to 11 million undocumented immigrants are obvious. Even Americans whose frustration has overcome their compassion and led them to support the harshest immigration enforcement would be likely to reconsider if they actually saw such an operation in action.