Although never explicitly codified in the Constitution, the axiom that a person is considered innocent until he or she has been proven guilty of a crime is a bedrock principle of our justice system. Indeed, the Supreme Court held in 1987 that while it is sometimes necessary to jail defendants before their trials — e.g., to avoid additional law-breaking or to prevent fleet-footed individuals from absconding — this is to be a “carefully limited” practice.

In a new paper published by the Texas Public Policy Foundation, my colleague Marc Levin and I show that while jail populations in counties of all sizes have grown substantially — by one estimate, America’s jail population was five times higher in 2013 than it was in 1970 — such expansive growth in urban, suburban, and medium-to-small-sized counties plateaued and began falling in 2005. However, growth in rural jails has continued.

Even in general terms, this sort of expansion puts strain on a smaller jurisdiction’s infrastructure. (Jails hold recent arrestees and those serving short sentences in addition to pretrial detainees; prisons handle those serving long sentences.) But pretrial populations in particular have grown as well, which presents us with additional questions. In Texas, for example, almost 33 percent of the jail population comprised pretrial detainees in 1994. However, by 2016, that proportion had grown to almost 74 percent. The national average currently stands at roughly 66 percent, up from about 50 percent in 1993.

Why has this happened? An increase in rural crime, perhaps the most obvious possibility, does not seem to explain it. In one of the most significant public feats in our history, overall crime rates have trended down to their lowest levels in decades since the mid 1990s. And while the drop has been most dramatic in cities, it has occurred in rural areas as well.

Or perhaps the key factor is a lack of court personnel available to evaluate individual defendants, which leads to them being detained until their trials. In rural areas this is particularly acute, even spurring some states to offer subsidies for qualified individuals willing to do this work. The large distances that some circuit judges must travel to cover multiple jurisdictions also creates a logjam of court cases.

Economic factors can play a role, too. Many local officials have built out additional beds to house inmates from other jurisdictions in order to receive daily per diems, which are commonly used to shore up flagging budgets and create a political constituency for excessive pretrial detention. Such was the experience in Grant County, Ky., which bore two relevant consequences. First, the general use of pretrial detention quadrupled. Second, their daily per diems dried up after an abuse scandal rippled through the system and the state removed its prisoners, leaving local taxpayers to foot the bill on construction costs for jail space they no longer needed.

This should ring a cautionary note: Easy money rarely lasts forever.

Another likely cause is the ongoing opioid crisis. National data don’t exist to directly attribute rural jail admissions to opioid-related arrests. Nonetheless, there has been a notable rise in drug arrests coinciding with the grim increase in opioid addiction. Rural counties in Kentucky experienced a 38 percent increase in heroin arrests between 2013 and 2016 alone (compared with 20 percent in urban counties), while heroin offenses in Ohio increased by a whopping 125 percent between 2011 and 2014. These are just two states. Small county jails do not commonly possess the infrastructure allowing them to absorb such a significant upward swing in new detainees on a daily basis or to release defendants under supervision. Therefore, more people remain in detention because sensible alternatives don’t exist.

Just as there are myriad reasons for pretrial-population growth, there are many possible solutions. The first is a necessity: There should be a presumption of release unless government can clearly articulate — preferably through validated risk assessment — a compelling public-safety or flight risk.

We need to protect public safety and ensure a defendant’s appearance in court, but the presumption of pretrial liberty must not get lost in the din.

Using risk assessment to better inform judicial release decisions is well supported by data. In the first six months after Kentucky adopted a new statewide risk assessment in 2013, the share of defendants released before trial rose slighty (from 68 percent the previous four years, to 70 percent), while new criminal activity by those released dropped by 15 percent. Court appearances remained stable during this period. In Texas, a recent comparison study by the Public Policy Research Institute showed that pretrial defendants released in the county using a validated risk-assessment tool committed 53 percent fewer violent felonies than those released from the county that relied on financial bail. Such data show that risk assessments do a better job of preventing both types of misclassifications: detaining lower-risk defendants who should be released and releasing higher-risk defendants who should be detained.

America also has too many criminal laws. In Texas alone, there are more than 1,700 statutory offenses, and only two do not (commonly) result in arrest. States should seek to reduce the number of these offenses that carry a possibility of jail time, allowing cases to be dispensed of more rapidly.

Pre-booking police diversion, such as the Law Enforcement-Assisted Diversion (LEAD) program pioneered in Seattle, represents an opportunity to identify individuals who may not need to be brought to jail — particularly for low-level drug offenses. Studies show that LEAD reduces recidivism among participants by 22 percent compared with a control group. Besides this obvious improvement in street-level crime, LEAD participants circumvent the traditional criminal-justice system — allowing them to avoid collateral consequences of a conviction while availing themselves of an opportunity to get help for an addiction.

There has been a noticeable tenor mounting across the country that rural areas have been forgotten in the hustle and bustle of American life. Growth in rural jails has been no different. We should use this recognition as an opportunity to reverse course. We need to protect public safety and ensure a defendant’s appearance in court, but the presumption of pretrial liberty must not get lost in the din.