In a surprising departure from his tough-on-crime image on the campaign trail, President Trump made waves two weeks ago by supporting a federal criminal justice reform bill. The president backed the First Step Act, backtracking on his opposition to a pre-midterm version of the bill. The legislation, long in the making and popular in both the Democratic and Republican caucuses, awaits only a vote in the Senate— one that Majority Leader Mitch McConnell appears to be intent on denying.

McConnell’s stonewalling has provoked fury among the bill’s supporters, who consider First Step an obvious reform. Iowa’s Chuck Grassley, who has authored a version of the bill, says it’s a “historic bipartisan bill,” that would amount to a “major bipartisan victory.” NBC News labeled it “the most sweeping set of changes to the federal criminal justice system since the 1990s.”

Backers of the legislation seem to both extoll the proposal and rush to emphasize its narrow scope. “Journalists/commentators should be clear that the bill applies only to federal cases, about 10% of the total prison system,” writes Council on Criminal Justice president Adam Gelb. Other reasons for supporting it verge on the inexplicable. Iowa Senator Joni Ernst, in announcing her support, cited “the disturbingly high rate of women—especially mothers—in prison.” This is a peculiar concern, given that all of the women in Bureau of Prison P custody couldn’t fill a quarter of Yankee Stadium .

The peculiarity of such hedges makes for a jarring contrast with the bill’s supposed historic scope. How can the bill be both sweeping and narrow in scope? The split response from law enforcement, one of the president’s key constituencies, has proven interesting. A few organizations have supported it, most prominently the Fraternal Order of Police . But scores more —including representatives of sheriffs, Assistant U.S. Attorneys, and drug enforcement officers — have criticized the bill.

Confusion among supporters and pronounced opposition from law enforcement should cause us to question whether the bill is as great as advertised. Does support for First Step derive from its merits, or from congressional leaders’ sense that they need to do something about America’s hulking, overstuffed prison system?

It is perfectly reasonable to believe something needs to be done to reduce the population of America’s prisons. Depending on how you count, America is the No. 1 jailer worldwide. Between prisons, jails, and other detention facilities, about 2.3 million people are currently locked up. According to the Sentencing Project , “[i]f current trends continue, one of every three black American males born today can expect to go to prison in his lifetime, as can one of every six Latino males—compared to one of every seventeen white males.”

But if the system is too big, the Fist Step Act might not be the appropriate fix. In its drive to act, Congress may pass a bill that would unduly free numerous federal offenders, including many drug traffickers and some 4,000 prisoners whose early release would come without regard to their future dangerousness. Furthermore, the current size and composition of the federal prison system render it not obviously ripe for reform—Congress should look to the states to take the lead instead.

This is because the federal system, relative to state and local incarcerations, is comparatively small: Just 8 percent of all U.S. prisoners are incarcerated at the federal level, about 180,000 people total. That number that has fallen year-over-year since 2012, down about 17 percent overall.

Of those in the system today, about 30 percent are incarcerated for immigration offenses (and are therefore mostly excluded from First Step). Another 30 percent are in for drugs, more than 97 percent of whom are drug traffickers (by contrast, there are only about 200 possession offenders). The remaining 40 percent are charged with a mix of fairly serious crimes: 12 percent for firearms offenses, 12 percent for fraud and other “white-collar” crimes, about three percent for child pornography offenses, and the remaining 10 percent or so for a mix of mostly violent offenses.

Advocates of criminal justice reform rely generally not only on the massive size of the system, but also the claim that there are many people incarcerated who do not deserve to be. But little about this composition suggests a there are many who are unjustly incarcerated—there are few if any of the “low-level, non-violent” drug offenders so often the poster-children for reformists. There are a fair number of white-collar criminals, but it is hard to see justice in reform which would disproportionately benefit white and wealthy offenders. Other classes (the First Step-exempted immigration offenders notwithstanding) do not command much sympathy.

Perhaps knowing that the statistics are not on their side, proponents of system-scale reform tend to rely on pathos-laden instances of injustice to make their cases. Alice Johnson, the grandmother of three and twenty-year prisoner whose life sentence for first-time, non-violent cocaine distribution was (thanks to the lobbying of Kim Kardashian West) recently commuted by Trump, springs to mind. But for every Johnson, there are dozens of inmates like Bin Wang, a Chinese drug trafficker who was recently convicted of distributing fentanyl responsible for a string of overdoses in Ohio. The burden of proof rests on reformers to show why the system is so unjust as to merit substantial changes, and why their changes are appropriate. Cases where justice may have been administered too harshly are why presidential pardons exist, a scalpel to the blunt instrument of the First Step act proposed by Congress.

How would First Step change the federal prison system? The bill would encourage prisoners’ participation in recidivism-reduction programming using the carrot of early release to post-prison supervised release. Its central plank is the “time credit” system . which awards participants credits for taking part in any of a wide array of programs: mentoring, substance abuse treatment, a prison job, etc.

Eligible prisoners can earn at least 10 days of time credit per 30 days of programming undergone; those assessed as “minimum” or “low” risk can earn 15 days , reducing their in-prison sentence by one third. Earned credits go towards release to a halfway house, home confinement, or supervised release . Although time credit beneficiaries would still be under some correctional supervision post-release, they would be substantially freer, in effect, a sentence reduction.

An effective and safe recidivism-reduction program needs to be careful about whom it includes. First Step acknowledges this, which is why it contains a lengthy list of federal offenses excluded from early prerelease custody. But this list is not lengthy enough. Conspicuously absent are offenses like transporting a minor for sexual purposes , forced enslavement , or threatening the life of federal officials. These are serious crimes, and reducing prison stays for such offenders does not accord with justice or public safety, which is why some in law enforcement have opposed the bill.

The most conspicuous omissions from the exclusions list, however, are drug-trafficking offenses. This is likely because of the (questionably true) story that U.S. prisons are stuffed to the gills with low-level, non-violent drug offenders. In service of this theory, First Step would release drug dealers to home detention or a halfway house, places from which it is comparatively easier to sell.

Drug offenders already have an impressively high recidivism rate: 77.5 percent are rearrested within five years of release. First Step aims to push down recidivism rates, but it will never do so perfectly, especially when dealing is a major or exclusive source of income for many offenders. As such, the benefit of lowering recidivism rates some must be weighed against release’s cost. 72,000 people were killed by drugs in 2017, making overdose the leading cause of non-medical death in the United States. New CDC data indicate that U.S. life expectancy fell for the third year in a row in 2017, thanks largely to drug deaths. is the public good really served by letting drug traffickers out earlier?

Trump’s pre-midterm opposition to First Step was largely because he did not want to release fentanyl dealers. In response, the revised version contains a new jury-rigged exclusion from the time credit system, but only for those found to be an “organizer, leader, manager, or supervisor” of a conspiracy to distribute fentanyl. Such an appellation — a “ role adjustment ” under federal sentencing guidelines — applies to just seven percent of all federal drug offenders, and therefore does not cover many fentanyl dealers.

Excluding only those convicted of distributing fentanyl has another unintended consequences. Specifically, it still permits early release for offenders convicted of distributing fentanyl-laced drugs, because prosecutors tend to not charge the hard-to-identify fentanyl offense. Fentanyl itself is addictive and deadly, but it’s now also routinely added as an adulterant to almost every other popular drug, from heroin to party drugs to cocaine . Thus, the fentanyl carve-out is really no carve-out at all, and fentanyl dealers—a group responsible for at least 30,000 deaths in the past year—could still readily be pre-released.

First Step also contains a similar exclusion for “organizers, leaders, managers, or supervisors” of heroin trafficking rings, but none for non-leader heroin traffickers. Nor does it exclude any trafficker of cocaine or prescription pills, no matter how senior. All three drugs were implicated in thousands of deaths last year; cocaine, for example, poisons almost as many people as prescription opioids. In a rush to reduce federal prison populations, Congress risks releasing as many as twenty-thousand dealers—15,000 or so of whom are likely to be rearrested within five years—back on to the streets when drug deaths are at a four-decade high .

The new time credit system isn’t the only concern. The bill also modifies federal “good time” credits — a distinct system by which prisoners earn actual time off their sentences (as opposed to supervised release) for good behavior. Under current BOP rules, prisoners are entitled to a maximum of 47 days of credit per year, but First Step would retroactively raise that number to 54 — a change which supporters acknowledge would lead to the release of some 4,000 federal offenders.

While First Step makes the “good time” system work the way it was originally intended to, the good time credit change is the closest thing to what Arkansas Senator Tom Cotton, who opposes the bill, has derisively called a “jailbreak.” It would unilaterally free thousands of federal offenders without any exposure to expanded anti-recidivism programming, regardless of how those individuals would be rated by First Step’s new risk assessment tool.

The expansion of the federal “safety valve” for low level offenders merits concern. Under current law , low-level, non-violent drug offenders with a prior sentence of less than 60 days can be sentenced without regards to federal mandatory minimums. The First Step Act enlarges this “safety valve” by allowing exemptions for non-violent and low-level violent offenders with up to two cumulative prior sentences of less than thirteen months each. It also adds a safety valve to the safety valve, permitting a judge to waive mandatory minimums in cases that do not involve a prior conviction for a serious drug or violent felony.

This amounts to a de facto suspension of many federal mandatory minimums, permitting judges far wider latitude to reduce the sentences of dangerous criminals. Indeed, there are cases in which judicial discretion is valuable, which is why the current system is merited; but granting free range to exempt offenders with significant criminal histories does not make sense. Mandatory minimums are a vital tool for law enforcement, which is why some law enforcement leaders have opposed the safety valve change.

There are numerous provisions in the bill which, if not urgently needed, are still good ideas. A ban on restraining pregnant women is eminently reasonable (though unlikely to apply to many); so too is the expansion of compassionate release to terminally ill inmates.

Also laudable is the bill’s measure to retroactively apply a 2010 law that reduced the enormous sentencing disparity between crack and non-crack cocaine dealers. The change has been unpopular with some First Step critics. That law, written by then-Senator Jeff Sessions, according to the U.S. Sentencing Commission, had essentially no effect on recidivism rates . Retroactively applying it would be a good thing.

Absent this, it is hard to see how these proposals are urgent enough, or impactful enough, to merit passing the full bill in the lame duck session without addressing its many problems. This is First Sep’s Achilles' heel: the urge to address over-incarceration is not solved by reforming the federal system, which mostly houses people who deserve to be there. When 92 percent of prisoners are locked up in the states, it is more important to look there for changes.

Many states—including major jailers like Louisiana and Texas —have already shown great initiative. A more effective bill might focus on inducing others to follow suit. Texas, for example, enjoyed great success by better funding its drug treatment programs, which can reduce recidivism and which helped get more offenders treatment faster; expanded federal support for such programs in other states would do the same. Louisiana worked to reduce the myriad fees it used to impose on prisoners (which can drive released offenders back to crime) — federal subsidies could offset lost revenue so as to encourage other states to do likewise.

There is even room for reasonable and limited sentencing reform in some states. Congress could use grants as an incentive to encourage early release for most possession offenders (who make up three percent of state offenders compared to less than one percent of federal offenders). They could also incentivize early release for older (55+) prisoners, who made up ten percent of state prison populations in 2013. Recidivism rates generally decline with age, and it is not necessarily worth incarcerating those who have “aged out” of crime—expanded old-age release is already in First Step for federal offenders, but would do as much or more good if states adopted it.