“ ‘Nobody is getting out of jail free, which is some of the characterization that is out there,’ said [Senator John] Cornyn, who describes himself ‘as conservative as they come.’ ’’ —The New York Times, Jan. 29

How quickly — or slowly — do shifts in the public attitude toward crime translate into major changes in federal law? US Senator John Cornyn is about to find out. As a former judge and state attorney general, the Texas Republican has solid law-and-order credentials. But he’s now leading an overdue bipartisan push to reduce prison sentences for some offenders and better reintegrate ex-cons into society.

In the 1980s and ’90s, broad apprehension about drug use and rising crime rates led lawmakers to ratchet up criminal penalties for a variety of offenses. Those changes came with a stiff price tag and, to the extent they’ve been empirically scrutinized at all, have had a limited effect on preventing crime. Expanded incarceration should be judged like any other policy: If it costs a lot and gets meager results, we need to change it.

The national mood has grown more forgiving. The US Supreme Court has scaled back the harshest penalties for juvenile offenders. Americans tell pollsters they prefer to fight drug crimes through treatment, not prosecution. States have liberalized their marijuana laws through voter initiative. Civil rights groups are now finding new allies among libertarians and fiscal hawks. A year ago, NPR recently noted, Iowa Republican Charles Grassley decried the possibility that sentencing reductions would let violent criminals out; now the Senate Judiciary Committee chairman is pushing for reforms.

Still, criminal justice policymaking turns on legislators’ gut judgments, and GOP hardliners such as Ted Cruz and Tom Cotton are already lining up against Cornyn’s efforts. Even if reforms lead to lower recidivism rates than the current policy, some number of released offenders will be arrested for other crimes. Old memories persist: In a meeting of Senate Republicans, majority leader Mitch McConnell reportedly raised the specter of Willie Horton, the convicted murderer who committed a brutal rape after being released in Massachusetts on a weekend furlough.

It was easy to persuade lawmakers of a generation ago to impose longer sentences for more people. In a more polarized time, rolling those laws back will be tough, even with Cornyn’s help.

Dante Ramos can be reached at dante.ramos@globe.com. Follow him on Facebook: facebook.com/danteramos or on Twitter: @danteramos.