Between 1980 and 2013, the federal prison population exploded, rising from 24,640 to 219,298, largely because of the war on drugs, which accounts for half of federal prisoners. Yet the National Association of Assistant U.S. Attorneys (NAAUSA) insists in a recent position paper that "our federal prison population is not exploding." How so? The number of federal prisoners fell slightly between 2013 and 2014, from 219,298 to 214,149. According to NAAUSA, that 2.3 percent drop makes up for the 790 percent increase that preceded it. Since balance already has been restored to the criminal justice system, it says, there is no need for sentencing reform.

The desperation reflected in such transparently misleading arguments is a hopeful sign for those of us who agree with former Attorney General Eric Holder that "too many Americans go to too many prisons for far too long, and for no truly good law enforcement reason." Bipartisan support for sentencing reform is stronger than at any point in recent memory, with the Obama administration and leading Republicans in both chambers of Congress united in viewing current penalties as excessively harsh. "I've long believed that there needs to be reform of the criminal justice system," House Speaker John Boehner (R-Ohio) said last month. "We've got a lot of people in prison, frankly, who, in my view, really don't need to be there."

Most Americans seem to agree. In an ACLU survey conducted last June, more than two-thirds of respondents said it is important to reduce the number of people behind bars, which includes about 2 million people in state prisons and county jails in addition to the 200,000 or so in federal prisons. The only thing preventing legislators from acting on that goal is bad arguments and the fear they inspire.

NAAUSA argues that sentencing reform is not just unnecessary but positively dangerous. It warns that "higher crime rates…will inevitably flow from the return of numerous federal drug traffickers to our communities at a significantly faster rate and the non-prosecution of many more." But while it's true that a rising prison population has coincided with falling crime rates in the last two decades, the relationship between those two trends is not as clear as NAAUSA implies.

Judge Alex Kozinski, whom Ronald Reagan appointed to the U.S. Court Appeals for the 9th Circuit in 1985, a few years into the imprisonment binge that gave us the world's highest incarceration rate, reflects on that dubious distinction in a recent Georgetown Law Journal article. "We are committed to a system of harsh sentencing because we believe that long sentences deter crime and, in any event, incapacitate criminals from victimizing the general population while they are in prison," Kozinski writes. "And, indeed, the United States is enjoying an all-time low in violent crime rates, which would seem to support this intuition. But crime rates have been dropping steadily since the 1990s, and not merely in the United States but throughout the industrialized world. Our intuition about harsh sentences deterring crime may thus be misguided. We may be spending scarce taxpayer dollars maintaining the largest prison population in the industrialized world, shattering countless lives and families, for no good reason."

The sense that the U.S. has gone overboard in locking people up is reinforced by the experiences of states that have enacted sentencing reform in recent years. In its response to NAAUSA's paper, Families Against Mandatory Minimums (FAMM) notes that "more than 30 states have reduced, eliminated, or reformed their mandatory minimum and drug sentencing laws over the past decade, and crime has gone down, not up." Between 2007 and 2012, according to a 2014 report from the Pew Charitable Trusts' Public Safety Performance Project, "the 10 states with the largest decreases in imprisonment rates had a 12 percent average reduction in their crime rates," while "in the 10 states with the largest imprisonment rate increases, crime rates fell an average of 10 percent."

Back in 2011, NAAUSA predicted that retroactive application of new, less harsh sentencing guidelines for crack cocaine offenses would have an "immeasurable crime impact." It was right. That policy, which the U.S. Sentencing Commission adopted against NAAUSA's advice, has not had a measurable impact on crime.

It makes sense that locking up more criminals would, up to a point, help reduce crime, even if only through incapacitation. But that approach requires locking up the right criminals: the ones who pose a threat to the general public because they hurt people or take their stuff, as opposed to the ones who commit arbitrarily defined offenses that violate no one's rights. NAAUSA refuses to acknowledge this crucial distinction, insisting there is no such thing as a nonviolent drug offender.

"It is well-established that drug trafficking is inherently violent," NAAUSA declares. It would be more accurate to say violence is a predictable feature of the black market created by a prohibition policy that NAAUSA avidly supports. Leaving that point aside, NAAUSA is saying it does not matter if the particular defendant a judge happens to be sentencing has never hurt a fly; he must pay for the crimes of others in his line of work. That hardly seems fair. Of the 22,000 federal drug offenders sentenced in fiscal year 2014, FAMM notes, just 16 percent had guns, and less than 1 percent committed acts of violence.

NAAUSA tries to redefine violence, arguing that "all drug dealing is dangerous, taking the lives of thousands of Americans, destroying families, and undermining the moral fabric of our communities, regardless of whether any individual offender engages in an act of violence during the commission of a drug offense." In other words, if I sell you heroin, and you die after injecting too much of it at once or (more likely) recklessly consuming it with other depressants, I may as well have murdered you. Likewise, presumably, if I sell you a bottle of whiskey and you die of acute alcohol poisoning after consuming it all in one sitting or from injuries sustained in a drunken car crash.

NAAUSA warns that sentencing reform will lead to an "increase in addiction" as drug dealers return to the streets prematurely, luring new users who otherwise would have escaped the bonds of pharmacological slavery. To anyone familiar with the economics of the black market, which replaces dealers as soon as they are arrested as long as there is a demand for their product, that prediction makes little sense. So it is not surprising that self-reported crack consumption continued to drop after Congress shortened crack sentences in 2010, as a new report from the U.S. Sentencing Commission (USSC) points out.

The USSC report debunks another NAAUSA claim: that "slashing minimum mandatory penalties will threaten the prosecution of many of the most dangerous and high level criminals involved in drug trafficking by undermining the cooperation incentive that the current sentencing structure creates." The sentencing commission found no evidence of such an effect. "Rates of crack cocaine offenders cooperating with law enforcement have not changed despite changes in penalties," the report says. "The rate of sentences that were below the guideline due to a government substantial assistance motion remained stable throughout the 2005-2013 period, indicating that the reductions in penalties during this period did not generally reduce the willingness of offenders to provide assistance to the government in the prosecution of others."

Similarly, after a new Justice Department policy reduced the number of drug offenders facing charges that carry mandatory minimums, defendants did not become less inclined to cooperate with the government. "One of the most common concerns that I hear expressed about eliminating or reducing mandatory minimums is that long sentences for low level defendants [are] the only way to secure cooperation against the worst criminals," Deputy Attorney General Sally Yates said in a speech last month. "Not only is this inconsistent with my personal experience as a prosecutor, it is inconsistent with the data we have gathered since the Department of Justice recalibrated our drug charging policy two years ago….Although some feared that defendants would stop pleading guilty and stop cooperating, our experience has been just the opposite. In fact, defendants are pleading guilty at the same rates as they were before we instituted the new policy. So the fear that not charging mandatory minimums would prevent us from being able to work our way up the chain just hasn't been borne out."

Even if NAAUSA were right that shorter sentences make federal prosecutors' jobs harder, that would not justify the current penalties. "U.S. sentences are vastly, shockingly longer than just about anywhere else in the world," Kozinski observes. While "elected officials, regardless of party affiliation and political leaning, seem to favor Draconian sentences, and the public seems to support them in the abstract," he says, there is evidence that politicians have overestimated voters' demand for harsh punishment. Kozinski cites an experiment in which James Gwin, a federal judge in Ohio, asked jurors in 22 trials to suggest appropriate sentences for the defendants they convicted. On average, Gwin reported, "jurors recommended sentences that were 37% of the minimum Guidelines recommended sentences and 22% of the median Guidelines recommended sentences."

Current sentences are especially arbitrary in the case of drug offenses, which are crimes only because legislators decided to treat them that way. Even if you agree with that decision, it is pretty hard to justify a 55-year sentence for a small-time marijuana dealer or a life sentence for a mild-mannered Deadhead who made the mistake of mailing LSD to a confidential informant. Likewise, how can anyone be confident that 10 years, rather than five or three, is the appropriate penalty for a second offense involving 28 grams of crack?

Because they decide which charges an offender will face and certify whether he has cooperated enough to avoid mandatory minimums, federal prosecutors wield enormous leverage in plea negotiations, as reflected in the fact that only 3 percent of defendants decide to go to trial. But when that decision can be the difference between a decade in prison and life in prison, something has gone terribly wrong. Coercing "cooperation" cannot be the overriding goal of criminal penalties, which must be constrained by principles of fairness and proportionality. At some point the interests of justice have to outweigh the interests of prosecutors.

This article originally appeared at Forbes.com.