Reforming intent standards has broad support from the conservative legal community, part of a broader shift there in favor of criminal-justice reform. “It’s not a huge barrier or hurdle to be proven, but it’s something that should be in there,” Holden told me. “We shouldn’t have people going to prison for things they wouldn’t necessarily know were illegal and had no knowledge or way to find out that they were.” The U.S. Chamber of Commerce and the Heritage Foundation backed Hatch’s bill, as did conservative senators like Mike Lee and Ted Cruz.

Support also came from criminal-defense organizations, a nontraditional ally for Republicans. Reimer, whose organization supports a default intent standard, framed the issue in moral terms. “The fundamental anchor of our criminal law, the moral anchor of our criminal law, is that people shouldn’t be punished unless they know they’re doing something wrong,” he told me. “That’s my elevator speech. And that’s the problem that we’ve been trying to address for many, many years now.”

However, some Democrats worry that by establishing a default intent standard, Congress would be making it harder for federal prosecutors to bring charges for regulatory offenses that currently lack an intent standard. “[This is] a category in which the public-health and safety concerns are so serious that you set out a criminal penalty as a boundary with the notion that corporations should stand well back from that boundary as part of protecting people from harm, whether it’s chemical emissions or benzene leaks or whatever it is,” Whitehouse explained.

Another notable skeptic is Chuck Grassley, who chairs the Judiciary Committee. During a committee hearing on mens rea in January 2016, he said he would be open to making smaller changes to intent standards. But the Iowa Republican rejected the broad proposal under consideration at the time. “Since strict-liability crimes do not set forth a state of mind, the House bill would change all of them to require that the defendant act ‘knowingly,’” Grassley said. “That would jeopardize public health and safety.” His office didn’t respond to a request for comment on the current bill.

“I completely and totally reject that,” Reimer said when asked about concerns that mens rea reform would help companies evade regulatory charges. He pointed to an NACDL survey of federal environmental laws that found that almost all of them, including the Clean Air Act and Clean Water Act, already establish some level of intent for criminal penalties. “I know the Federal Defenders now are endorsing it, and they’re certainly not doing it because it’s going to help polluters,” he added.

Both sides cited mens rea as one factor among many that doomed sentencing reform last year. “It all came up rather suddenly, with the world’s fastest hearing being scheduled in Judiciary and sudden declarations of the House that nothing would be done on sentencing reform without mens rea being thrown in,” Whitehouse said.