Sometimes you find solutions in the most unlikely places. A Pittsburgh paper last month found the keys to reforming out-of-control federal immigration prosecutions that warehouse people in substandard private prisons amid horrific conditions. The solution is pretty simple: Prosecutors should use the discretion that their office affords them and follow the Department of Justice’s “Smart on Crime” principles “[t]o ensure finite resources are devoted to the most important law enforcement priorities.”

That’s what is happening in Western Pennsylvania. U.S. Attorney David Hickton, whose district covers Pittsburgh, Erie, and Johnstown, has decided that prosecuting immigrants for border crossing without aggravating factors is a poor use of his limited resources. “We touch Canada through Lake Erie and Erie, Pa., but we had, when I got here, one of the highest percentages of immigration cases (outside of the Southwest border states),” he told the Pittsburgh Tribune-Review. “Certainly in my judgment, it was out of whack with the risk in this district.”

He isn’t the first top federal prosecutor to make this point. Hickton’s counterpart in the Western District of Texas, Richard Durbin, recently spoke similarly to the U.S. Sentencing Commission. He testified that he’s not convinced of any deterrent effect from the numerous illegal entry prosecutions referred to his office by Customs and Border Protection.

Illegal entry and illegal reentry prosecutions exploded over the last two decades. Total criminal immigration prosecutions increased from under 10,000 in 1997 to 40,000 in 2007 and almost 100,000 in 2013, before modest declines more recently to about 80,000 annually — due in part to officials like Hickton exercising good judgment. In the last year, Hickton prosecuted just 15 people for immigration crimes, or 5 percent of his docket.

That compares with a high of 85 people in 2012, when 42 percent of cases in the district’s Erie division were immigration prosecutions. Every unnecessary immigration prosecution takes resources away from more important priority cases and compounds immigration offenses' voracious effect on the federal criminal docket, which saw these prosecutions' share increase from 2 to 26 percent since 1992. The Department of Justice’s own priorities are national security, violent crime, financial fraud, and protection of the most vulnerable members of society, not throwing migrants into federal prison for returning to their American citizen children.

Many of those sentenced have deep family and other ties in the United States. Judge Robert Brack in Las Cruces, New Mexico, told The Wall Street Journal in 2013: “Every day I see people who would never have been considered as criminal defendants two years ago. It’s just a completely different profile.” Half of those sentenced for illegal reentry had at least one child living in the United States, and two-thirds rejoined relatives other than children. Sentenced reentrants have an average (and median) age of 17 at the time of initial entry, and their average age at prosecution is 36, meaning that many grew up in the American communities to which they tried to come back.

There's even no persuasive evidence that these expensive prosecutions and sentences achieve any deterrence. The Department of Homeland Security’s Office of Inspector General issued a critical report last year concluding that “Border Patrol is not fully and accurately measuring [border prosecutions’] effect on deterring aliens from entering and re-entering the country illegally” and noting that Border Patrol’s “current metrics limit its ability to fully analyze illegal re-entry trends over time.”

A University of Arizona study tracking 1,200 people deported found that there is no statistically significant reentry difference between those who went through prosecution and those who did not. The Migration Policy Institute has noted that for border crossers with strong family or economic ties (or both) to the United States “even … high-consequence enforcement strategies [i.e., criminal prosecutions] may not deter them from making future attempts.” So all these resources are being used to throw the federal code at migrants on a guess that prosecutions on a mass scale — rather than targeted at individuals with aggravating factors — dissuade mothers and fathers from trying to reunite with their kids.

U.S. Attorney Hickton’s wise decision will save significant taxpayer money and protect up to 70 migrants a year from wasteful, inhumane incarceration. The deluge of immigration prosecutions continues across the country, however. In every judicial district prosecutors should reassess whether locking migrants up for crossing the border truly furthers their priorities, or simply piles unjust hard time on top of a broken immigration system.