Family separation really bothered me too (as you can tell). Unfortunately, it is America. Not America as I want it to be, but America as it is now — and has been before, with Japanese-American internment a prime 20th century example.

I don’t know if any political system, laws, or constitution could always prevent it. The problem with laws is they only work if people voluntarily follow them or are forced to. That applies more strongly to norms. If the people in charge don’t voluntarily follow or enforce them, and those with the power to check and balance the executive (i.e. Congress) choose not to act, there’s not much the system can do in the short-run.

However, the biggest check-and-balance in the American system is regularly scheduled elections. If Americans don’t want deliberate cruelty towards migrants, they can (and should) vote against that policy’s architects and apologists.