Oh, how I hate the principle of letting private firms incarcerate prisoners.

Yet, according to USA Today, the private-prison industry thinks it’s about to score big if Donald J. Trump goes ahead with his plan to round up millions of people who are in the United States illegally.

These outfits have given big money to Trump and now see a potential payoff if the president follows through with his pledge to put all the illegal immigrants behind bars before deporting them.

Let me offer this notion about private prisons.

First of all, the public already pays police officers, prosecutors, judges and juries to arrest, detain and prosecute criminals. The public, therefore, ought to be responsible for their incarceration when they are convicted of crimes.

It’s a social responsibility thing, the way I see it.

Second of all, if the president believes illegal immigration presents a dire threat to our national security, our way of life and our national identity, doesn’t that mean that the public should step up and foot the bill for these alleged threats?

Here is how USA Today reports the issue: “Earlier this week, the Department of Homeland Security issued sweeping new instructions to carry out Trump’s executive orders on immigration. They require all federal agents — including Customs and Border Protection (CBP) and Immigration and Customs Enforcement (ICE) — to identify, capture and quickly deport undocumented immigrants.

“Significantly for private-prison operators, the orders also require that undocumented people caught entering the country be detained until their cases are resolved, ending the ‘catch and release’ program in which undocumented immigrants were processed by immigration agents, released into the USA and ordered to reappear for court hearings.”

So now the Trump administration wants to farm out this responsibility to for-profit prison companies? I’m trying to understand where the nation derives the cost savings if it is going to pay these companies to do what state and local authorities should be doing.

And I haven’t even mentioned the public oversight of the manner in which these private lockups are managed.

The idea of private prisons is loony, in my view. If we’re going spend public money to send criminals to prison, we need to spend public money to ensure they are treated humanely.

And that includes illegal immigrants.