In its subtitle, Barry Latzer’s latest book promises both a “defense of the American justice system” and a “proposal to reduce incarceration while protecting the public.” It does a third thing, too, in its 200 pages, offering a fairly intensive history of punishment in this country before proceeding to the other two topics.

That history is immensely informative. Early colonists were whipped or held in the stocks for such sins as working, hunting, or kissing their wife on the Sabbath; more serious crimes resulted in branding, exile, or public hangings. Circa 1800, penitentiaries entered the arena, along with a faddish belief that solitary confinement could purify prisoners’ minds of society’s bad influences. Oddly enough, while some had advocated penitentiaries as a more humane alternative to corporal punishments, many prisons themselves whipped their charges as a form of discipline or subjected inmates to brutally hard labor. The post–Civil War South was home to the “convict lease,” which entailed renting prisoners out to private companies in need of back-breaking labor. Decades later, as progressives made inroads in the North, the South held on to prison farms and chain gangs.

This history is in marked contrast with the current state of things, thanks to concerted reform efforts that unfolded over many years. As Latzer puts it,

in the last fifty years, corporal punishment, the death penalty, and overt racism have become rarities. Prisoners today are permitted family and conjugal visitations; they have libraries, gyms, television, email, and internet access; they get free lawyers to handle their appeals as well as advanced medical care in case of health problems — all at public expense.

But the mere fact of improvement doesn’t show that things are what they should be, of course, so Latzer then responds to some common criticisms of the U.S. justice system.

The basic facts at the root of the debate are these: The U.S. imprisonment rate roughly quintupled between the 1970s and the mid 2000s, cresting at about 500 prisoners for every 100,000 residents. Since then, the rate has ticked down closer to 400 per 100,000. (This amounts to about 0.6 percent of the 18-and-over population.) The prison population is disproportionately black. And the U.S. incarcerates several times as many people per capita as similarly developed countries do.

Latzer argues that these facts are not indictments of the system.

Yes, the imprisonment rate shot up during the last quarter or so of the 20th century. But that buildup was a response to a similarly dramatic increase in crime, which in its early stages was met with an ineffectually lenient response. Further, after crime fell for a while starting in the 1990s, imprisonment started declining too.

Yes, the incarcerated are disproportionately black. But incarceration statistics roughly track various measures of how often members of different racial groups commit the serious types of crimes that typically lead to prison. As Latzer writes, arrests for these crimes are “not discretionary” — cops have to arrest the perpetrators if they find them — and serious crimes reported to police are not more likely to result in arrests if the perpetrators are black. These cases are also vetted by prosecutors, defense attorneys, and sometimes juries much more carefully than other arrests are. Latzer doesn’t fully disprove the existence of any racial bias, but he provides compelling reasons to reject the narrative of racism as the primary driver of black incarceration.

Yes, the United States has a far higher overall incarceration rate than other countries. In addition, if you look at the typical time served for a specific offense, someone convicted in the U.S. will probably spend about twice as long behind bars as someone convicted in Europe. Americans probably are a bit more punitive than Europeans are, but these disparities are somewhat more complicated than they seem. For example, the U.S. has a far higher murder rate than other rich countries, and while murders are a low percentage of all crimes, they contribute disproportionately to incarceration. The U.S. also has higher rates of gun use in crime, which drives enhanced sentences.

It helps to look at the numbers in more qualitative ways as well. Would the typical person think that the system is overly harsh, given how assorted offenses are treated and who ends up in prison for how long?

Latzer notes that most crimes go completely unpunished: The number of prison admissions for murder each year, for example, is only about half the number of murders, primarily because so many murders are never solved. For rape, robbery, and aggravated assault, the comparable numbers are far lower, with prison admissions totaling only about 5 percent of the number of crimes committed. Latzer notes that even among those caught, “31 percent of all convicted felons and 23 percent of violent offenders are released without spending a single day in prison.”

Meanwhile, more than half of state prisoners are serving time for violent offenses, with the remainder divided among property crimes, drug offenses, and “public order” crimes such as drunk driving and weapons violations. (Drug offenses are much more common in federal prisons, but federal prisons house only a small minority of all inmates. And those who do serious time for drug offenses are normally traffickers, not mere users.) Among inmates released in 2016, the median time served amounted to 13 years for murder, four years for rape, three years for robbery, and less than 18 months for burglary, assault, or drugs.

One can certainly argue for more-lenient treatment of certain offenders, especially where drugs are concerned. But in general, the numbers do not show punishments that are wildly out of step with the harms inflicted.

Nonetheless, prison is expensive and serves largely to warehouse offenders so they can’t commit more crimes. Once incarceration’s retributive purpose has been served in a given case, we should be open to releasing the offender earlier than we currently do — so long as the perpetrator no longer poses an unreasonable risk to others. And at any rate, when political pressures force legislators to decarcerate, this should be done in the least harmful way possible. Latzer proposes “e-carceration,” an idea he has previously discussed in this magazine (“Let Them Wear Bracelets,” March 1, 2018).

Basically, if you slap a GPS bracelet on an offender, it can track where he goes — and justice systems throughout the world are experimenting with this kind of technology, with very promising early results. The bracelet can alert the police if the offender goes somewhere he shouldn’t (such as the home of a witness against him), fails to go somewhere he should (such as work or a meeting with a parole officer), or tries to take the monitor off. The data collected can also be used to match the offender’s location with the times and places of new crimes.

In some cases, GPS monitoring coupled with strict travel rules — up to and including full home confinement — could conceivably be a workable alternative to incarceration. Say what you will about the privacy implications, but a GPS bracelet is a lot less intrusive than a prison cell with full-time guards. There are, however, some limits to the technology, including that it requires manpower to monitor violations, and that it won’t necessarily be able to tell if the offender commits a new crime while ostensibly being monitored.

Because the technology still has a ways to go, Latzer suggests, to start, focusing our efforts on parolees, probationers, and those on pre-trial detention. This makes a lot of sense, but left-wing justice reformers might balk. Monitoring individuals not currently in prison increases the justice system’s supervisory powers. What if the rollout stops there and we never get to the part about decreasing incarceration?

Latzer doesn’t acquit the U.S. justice system of every last charge leveled against it; that would be impossible in such a short book. But he provides an important corrective to much of the justice-reform narrative, alongside a fascinating history of punishment in America and a proposal that could markedly reduce incarceration — eventually.