“Compromise struck on criminal justice reform,” touted a Politico headline in April. Five months later, the New York Times had to explain Why the Senate Couldn’t Pass a Crime Bill Both Parties Backed.”

But there is still a tiny sliver of hope for reformers, captured in yet another headline, also from Politico: “Ryan pushes sentencing reform in face of skeptical GOP.” Evidently, House Speaker Paul Ryan is considering making one last drive during the lame-duck session, when the election will be over and many legislators will have, as President Obama once put it, “more flexibility.” It will be a long shot, especially as Senate Majority Leader Mitch McConnell says he doubts his chamber can handle the issue in the time remaining.

But whether the effort is moribund or on the verge of springing back to life, this is a good time to review what it seeks to accomplish and why it has struggled so mightily, especially to win support from conservatives.

As I wrote in June, done carefully, justice reform can shrink the government, save money, and help ex-offenders get their lives on track without threatening public safety. Whatever justification there was for increasing incarceration decades ago, that trend continued longer than it needed to, and incarceration rates remain unjustifiably high. However, while many conservative intellectuals embrace these arguments, the case has not really trickled down to conservatives on the ground. Some red states have passed reforms, but in general conservatives are more skeptical of reform than liberals, and incarceration has fallen more in liberal states than in conservative states since 2007.

The federal effort is a test of whether Republicans nationwide can really get behind justice reform, and the prospects look dim.

The compromise Politico touted in April—a revision to the Senate’s Sentencing Reform and Corrections Act—was modest in scope. To set the stage, the federal system houses just 13 percent of American prisoners, and a disproportionate share of them (about half) are drug offenders. The average period of confinement doubled between 1988 and 2012, to more than three years, while admissions rose by an even greater proportion. About half of federal drug offenders now receive five- and ten-year mandatory minimum sentences. Some can be sentenced for much longer, especially if they carry weapons while dealing drugs or refuse plea deals.

In that context, the bill would lower some mandatory minimums and allow broader exceptions for others, focusing on drug and other nonviolent offenders with limited criminal history, as well as those facing extremely severe sentences under the status quo. (Repeat drug offenders who also have violent convictions on their records can get life sentences.) Further, it would actually increase sentences for some crimes involving domestic violence, terrorism, and the dangerous opioid Fentanyl.

The increased Fentanyl sentences hint at one reason the effort has struggled. Many Republicans haven’t backed away from their old tough-on-crime stances, and legitimately worrisome trends have given them ammunition—most prominently an opioid and heroin epidemic spinning out of control and a murder rate pushing upward again after two decades of decline. Donald Trump’s emphasis on “law and order” further complicates matters. Even with some former critics like Sen. Chuck Grassley on board, passing justice reform in a Republican Congress is difficult in this environment.

Not all the obstacles stem from intra-GOP squabbling, though—Democrats and Republicans have also fought over “mens rea” reform. House Republican Bob Goodlatte recently vowed there would be no justice reform without it, while Democrats call it a sop to white-collar criminals.

Mens rea translates literally as “guilty mind”—usually, prosecutors must prove a defendant had one while committing the alleged crime. But different aspects of a person’s mental state are relevant in different contexts. Did they not even realize they were smuggling heroin, because someone else hid it in their bag without them noticing? Did they act recklessly behind the wheel, even if they didn’t outright intend to cause harm? Did they toss leaves into a bonfire intentionally, but not know it was illegal to do so? Did they have a duty to look up the rules before they acted, or was their behavior so innocuous that the typical person would not even consider the possibility that they might be breaking the law?

In statutes, these concepts are invoked through the use of words like “knowingly” and “willfully.” But many statutes don’t have any mens rea requirement at all. If these laws are enforced literally—as “strict liability” crimes, meaning one’s intentions are irrelevant—people can be thrown in jail for things they didn’t even do on purpose, or for behavior that hardly anyone would suspect to be illegal.

In practice, when law-enforcement agencies have failed to use their discretion to avoid such abuses, courts have often made up their own mens rea rules—in fact, Supreme Court precedent requires this for felonies—but these are inconsistent across courts, and abuses do slip through the cracks. One snowmobiler was convicted because, caught off-guard by a blizzard, he got lost and ended up in a National Wilderness Area where snowmobiling was not allowed; another family ran afoul of the Migratory Bird Act when a young girl rescued a woodpecker (though the agency dropped the $535 fine following a public outcry).

To address this problem, Republicans would like to comb through all the laws, identify the ones without mens rea requirements, and add whatever language is appropriate to each crime. Just kidding: our elected representatives would never take on the responsibility of maintaining the enormous collection of statutes they expect us to follow. Instead, the various proposals are for one-size-fits-all solutions, such as a baseline mens rea standard for all statutes without one.

Give them credit; they’re trying. But liberals warn—joined by the Justice Department—that Republicans’ proposals could make it difficult to prosecute corporate crime, allowing powerful executives to use ignorance of the law (or ignorance of what was going on at their own businesses) as an excuse. Republicans, for their part, seem determined not to budge.

Again, by all accounts, Ryan faces long odds if he tries to revive these stalled efforts. After that, all will depend on who ends up controlling Congress and the White House next year.

Robert VerBruggen is managing editor of The American Conservative.

Editor’s note: the description of the Migratory Bird Act case in this article has been clarified.