Zero tolerance policies have been spreading throughout America for the past 40 years, wreaking havoc wherever and whenever they've been tried. That's because their fundamental premise is that the cause they aim to advance is so righteous that authorities have impunity to go after minor offenses with maximal force.

It should come as no surprise, then, that the results would be deeply ugly now that the Trump administration has deployed a zero-tolerance policy against the world's most powerless people: fleeing migrants.

Zero tolerance became all the rage in the 1980s when President Ronald Reagan launched his War on Drugs, and the smallest drug offenses got treated like existential threats to the fabric of American society. This led to mandatory minimum sentencing laws that turned America into the incarceration capital of the world by stripping judges of any discretion in keeping sentences commensurate with the crime. The upshot has been that nonviolent drug offenders like Alice Johnson, whom President Trump granted clemency to this week after 20 years in jail, got a life-without-parole sentence. There are millions like her languishing in jail.

Meanwhile, civil asset forfeiture policies, the other gift of the zero tolerance approach to drugs, handed law enforcement officials the power to confiscate any physical asset they suspected of being used in a crime without bothering to obtain convictions. Despite a massive public outcry, forfeiture spread like wildfire and became a standard part of policing — no doubt because the seized assets are lucrative for law enforcement salaries and budgets.

Reagan, a Republican, invoked zero tolerance policies to fight drugs. A few years later, Bill Clinton, a Democrat, invoked them to fight guns in schools. Soon enough, schools used zero tolerance to fight every classroom ill from drugs to unruly behavior.

Stories of toddlers and teens suspended, expelled, and even prosecuted for the most trivial offenses — like bringing nail clippers and scissors to school — are legion. An eighth-grade girl was booted out for giving a Midol without prescription to a friend experiencing menstrual cramps. An 11-year-old autistic, black kid who kicked a can in anger was handcuffed, charged, and prosecuted for disorderly conduct. The worst hit are poor, minority kids who can't afford expensive lawyers to fight back when expelled or charged, prompting the ACLU to dub such zero tolerance policies for minors a "school-to-prison pipeline."

But none of this compares to the hideousness transpiring at the border, where this administration has unleashed zero tolerance policy against desperate migrants fleeing poverty and violence.

Unlike previous administrations, which handed first-time border-crossers to ICE for deportation, the Trump administration has pledged to criminally prosecute "100 percent of illegal southwest border crossings" before deporting them — despite the fact that immigration prosecutions already constitute half of all federal prosecutions. Even asylum seekers, a group protected by both domestic and international law, are not spared if they are caught between ports.

The point of prosecuting prior to deportation is to create a criminal record against these folks so that if they try and enter again, they can be charged with a felony and thrown in jail, ending so called "catch and release." Previous administrations handed prosecutorial discretion to border authorities so as to target prosecutions to violent criminals and drug smugglers rather than ordinary migrants searching for safe havens or jobs. That's because prosecution triggers the most horrific consequences — completely disproportionate to the offense. Under current law, for example, once someone is branded a criminal, he or she forfeits rights to their children. That's why, once this administration decided to prosecute everyone, it also had to embrace separation as its default policy rather than as a rare punishment aimed at genuine criminals, even if that meant tearing away 18-month-old infants from mothers and sending them off to detention facilities thousands of miles away. And make no mistake: The Trump administration relishes the deterrence value of such barbaric actions, as it has openly admitted. It is ripping about 65 kids from their parents daily.

In theory, criminal prosecution obliges Uncle Sam to extend due process to these migrants, including legal representation and a court hearing. But Attorney General Jeff Sessions, the architect of the zero tolerance policy, is making a mockery of that requirement.

He has scrapped the Legal Orientation Program that allowed nonprofit organizations to help migrants facing deportation understand the Kafka-esque immigration legal code on which their fate hangs. He also did away with the requirement that immigration judges hold hearings on each asylum case — which basically means that these judges have little information to make determinations independent of the recommendations of detaining agents. This hands these agents, usually no friends of the asylum seekers, even more power, inviting exploitation and abuse.

In addition, Sessions imposed a 700-deportation quota on immigration judges. And to help them fulfill it, he has doubled down on Operation Streamline, the horrendous Bush-era practice of holding mass trials that lump everyone — coyotes and asylum seekers alike — into a single court session.

A few hours before the session, a single attorney is introduced to some 40 handcuffed and shackled migrants whom he has to represent. He usually obtains the same plea deal from all of them to sign away their rights and agree to be deported — never mind that they are often confused and don't understand English, much less America's legal procedures, and have little idea what is happening to them. Then the judge asks them en masse if they plead guilty, they all say "si," and, lo and behold, their fate is sealed.

Such assembly-line justice has bumped prosecutions for illegal entry 448 percent from March 2017 to February 2018, even though border crossings are at an all-time low.

The human toll of all this is simply unimaginable. A reporter at The Intercept attended some of these post-zero tolerance trials in Brownsville, Texas, and describes a heart-wrenching scene in which the presiding magistrate, Judge Ronald G. Morgan, a Bush appointee, became so visibly distraught after a few days of mass trials, he couldn't do it anymore and started to individually question the migrants. Many of them wailed and asked him if their kids would be reunited with them in detention camps now that they had agreed to be deported. He gave them false assurances that they would. But he was so overcome that he told the detention officer in court that if he wanted to "imagine hell" then this is "probably what it looks like."

Zero tolerance policies represent the Trotskyite "by any means necessary" version of law enforcement in which authorities, in their zeal to throw the book at people, are allowed to throw out the rule book without regard to proportionality or due process. They are turning America's southern border into a house of horrors that if allowed to persist will rival the stain of the Japanese internment during World War II.

America can survive the transgressions that zero tolerance policies are designed to address. But it can't survive a government that plays by the rules of neither justice nor humanity.