Criminal-justice reform is one of the few bipartisan issues gaining traction in Congress right now. Politicians from the left, the right, and the center now recognize the need to reduce the United States’ unprecedented prison population. But an immigration bill under debate in Congress shows that the impulses that created mass incarceration still run strong in American politics.

In July, a group of legislators introduced the Establishing Mandatory Minimums for Illegal Reentry Act of 2015, popularly known as Kate’s Law. On Wednesday, the U.S. Sentencing Commission estimated that Kate’s Law would expand the federal prison population by over 57,000 prisoners, according to Families Against Mandatory Minimums, a nonprofit organization that supporters sentencing reform.

Kate’s Law is named after Kate Steinle, who died on July 1 after being shot on Pier 14 in San Francisco. Police arrested Juan Francisco Lopez-Sanchez, a Mexican national and convicted felon who was in the United States illegally, and charged him with Steinle’s murder. Lopez-Sanchez subsequently admitted to firing the gun, but claimed Steinle was not the target and that her death was accidental.

Steinle’s death set off a firestorm of protests among opponents of illegal immigration. Donald Trump transmuted some of the outrage over Steinle’s death, as well as his broader invectives against illegal immigration and “political correctness,” into frontrunner status in the Republican presidential-nominee race. On a July 6 segment that defended Trump’s comments, Fox News Channel host Bill O’Reilly urged his cable audience to lobby Congress on a mandatory-minimum provision he called Kate’s Law. The following night, he clarified his proposal even further.

As we suggested last night, Congress should pass legislation that would impose a mandatory-minimum five-year sentence on any illegal alien that is deported and then comes back.

“The word mandatory is crucial,” O’Reilly told his audience. “There are laws on the books now that are being ignored. Congress must write Kate’s Law so if officials do not enforce the mandatory sentence, they themselves can be prosecuted.” Steinle’s parents endorsed the measure in a July 13 interview with O’Reilly. The House bill currently has 45 cosponsors; Senator Ted Cruz drafted an identical version in the Senate on July 14.

If the proposal became law, its impact would be dramatic. “Kate’s Law would suck up every dime you saved from criminal-justice reform and negate it,” said Molly Gill, a government-affairs counsel at FAMM. Undocumented immigrants typically serve between 15 to 18 months in prison under the current sentencing laws before deportation, Gill said. O’Reilly’s proposal would boost that average by 300 percent. Housing the Kate’s Law inmates for longer periods of time would cost the U.S. Bureau of Prisons an estimated $2 billion per year, according to FAMM. The bureau’s annual budget request for all of 2015 was $7 billion.

O’Reilly’s proposal stands out in a political atmosphere that is increasingly critical of mandatory-minimum sentencing, including among conservatives. For this reason, some legislators who embraced sentencing reform are wary of the new proposal. Republican Senators Mike Lee and Jeff Flake publicly opposed Cruz’s mandatory-minimum bill in August. The Senate Judiciary Committee will consider adding it to a bill that defunds so-called “sanctuary cities,” a term for municipalities that don’t enforce federal immigration laws, during a committee hearing on September 10.

Despite the public rancor, immigrants are generally less likely to commit crimes than the native population, according to the The Wall Street Journal. Mandatory minimums are generally ineffective at reducing crime or recidivism. Anti-illegal-immigration advocates who complain about the burden on the American taxpayer might find a 28 percent increase in the federal prison budget counterproductive. But these are relatively minor points in the debate. What matters is the all-too-familiar refrain: Something must be done.

We’ve heard this logic before. Consider the summer of 1986, when media coverage of crack cocaine reached its peak. Newspapers and TV stations had spent previous months reporting on the drug’s effects in inner-city neighborhoods. But the real frenzy began in June when Len Bias, a 22-year-old basketball prospect hailed as the next Michael Jordan, died of a cocaine-induced heart attack two days before the NBA Draft.

Reagan administration officials and congressional aides cited Bias’s death as a turning point in Washington’s response to the issue. Members of Congress were also eager to act ahead of the November midterm elections. Something had to be done. Legislators swiftly introduced legislation after the summer recess and passed the lengthy Anti-Drug Act of 1986 on October 17.

On the 20th anniversary of Bias’s death in 2006, criminal-justice-reform activists Eric Sterling and Julie Stewart wrote about the Act’s effects:

One result was the innocuous-sounding Narcotics Penalties and Enforcement Act, which became the first element of the enormous Anti-Drug Abuse Act of 1986, hurried to the floor a little over two months after Bias's death. But the effect of the penalties and enforcement legislation was to put back into federal law the kind of clumsy mandatory minimum sentences for drug offenses that had been done away with 16 years before. And there they remain, 20 years and several hundred thousand defendants later...

Not surprisingly, the federal prison population has exploded. From 1954 to 1976, it fluctuated between 20,000 and 24,000. By 1986 it had grown to 36,000. Today it exceeds 190,000 prisoners, up 527 percent in 20 years. More than half this population is made up of drug offenders, most of whom are serving sentences created in the weeks after Len Bias died.

The growing bipartisan consensus on mass incarceration is often seen as a slow, moral rousing from deep slumber. But even in November, 1986, less than a month after the Act sailed through Congress, legislators knew they had acted too hastily:

The House Democratic leader, Jim Wright, who was designated to head the effort, later said his most pressing concern was that Congress act before television lost interest in the drug story.

“One of the unfortunate by-products of the television age is the short attention span of the American public,” the Texan said. “We walk along fat, dumb and happy until a crisis grabs us by the throat. Once it is off the front burner of nightly television coverage we go back to sleep.”

The Republican leader in the House, Robert H. Michel of Illinois, said that he feared that unless House Republicans joined in quickly, the Democrats could grab the issue as their own in time for the election.

“If we had more time we could have more carefully considered” some of the more controversial provisions, Mr. Michel said, but “we just had no alternative.”

Something had to be done.