I’m not going to pretend to be an expert on this topic, but I’m going to lay out what appears to me to be true about the fiasco at the border.
First, illegal entry into the United States is a crime. If you enter the U.S. illegally, you can be prosecuted. If you are charged with illegal entry, you will be detained, and our law requires that adult criminal detainees be kept separate from children, which isn’t generally unreasonable.
(Note: not all people who enter the U.S. without authorization are entering illegally. Illegal entry requires that one either “(1) enter or attempt to enter the United States at any time or place other than as designated by immigration officers, or (2) elude examination or inspection by immigration officers, or (3) attempt to enter or obtain entry to the United States by a willfully false or misleading representation or the willful concealment of a material fact.” In theory, one can show up at a designated port of entry at the right time and present oneself to immigration officials to request asylum. My understanding, however, is that CBP has been blocking asylum seekers from entering legally. So they’re entering illegally instead. It’s worth noting that the aforementioned CBP practice appears to violate immigration law.)
Second, not all crimes need to be prosecuted. Prosecutorial discretion, for better or for worse, is part of our system. This means that, in certain circumstances, prosecutors can decline to charge people who may have committed crimes. One of the ways that the executive branch of our government effects policy changes is by laying out enforcement priorities. Of course, it’s possible to go too far with this, to the point at which the executive is no longer faithfully executing the laws. But faithfully executing the laws can’t mean a 100% prosecution rate for all crimes, in part because that’s impossible to achieve.
Third, there are some really good reasons not to charge at least some illegal entrants with illegal entry. For example, it is presumably more expensive to conduct criminal proceedings (which must be before an actual Court) than to conduct civil deportation proceedings (which are held before Article II immigration judges). Moreover, it is presumably undesirable (unless you’re Jeff Sessions) to separate children from their families, especially when doing so makes the whole immigration process more chaotic and costly for everyone involved. What’s more, at least some of these entrants will attempt to claim asylum, and at least some of these claims will be meritorious, and prosecutions against them will fail. The economic and moral cost of charging every illegal entrant is sufficiently high that you can make a strong case against charging every illegal entrant.
Now, Sessions implemented this zero-tolerance policy because he has deemed it expedient to separate parents from children, as this will deter illegal entry. He has made the judgment that, in spite of the cost of prosecuting every illegal entrant, which includes the cost of figuring out how to hold parents and children in separate detainment facilities without losing track of where people are, is outweighed by the good of deterring illegal entry. And this deterrence is supposed to be achieved by separating families. You may have heard the moral principle that we ought not to do evil that good may follow. But that’s exactly what the government is doing. They are separating families in order to deter people from entering the country illegally.
Our immigration system is a mess. It’s way overloaded with pending asylum applications, and we don’t have sufficient facilities to hold everyone who has crossed the border while we process their claims. There isn’t a simple and humane solution for the overload our system is dealing with. Nevertheless, the existence of a serious problem does not justify the Trump administration’s use of the suffering of children as a deterrent and/or political bargaining chip. This policy is evil and it should be changed.