Hillary Clinton's dishonest crime dodge: Her Columbia speech betrays a failure to understand the forces that have made America safer

It is easy to forget that, in 1991, the U.S. murder rate was well over twice what it is today. In a speech last week at Columbia University, Hillary Clinton demonstrated she doesn’t understand that ending what she called the “era of Mass Incarceration” will endanger lives.

These days, it’s popular to sympathize with criminals. We saw this when Baltimore Mayor Stephanie Rawlings-Blake “gave those who wished to destroy space to do that” and ordered police to “stand down.” We saw it again when she failed to return the governor’s calls, as he repeatedly tried to get her permission to send in the National Guard. She even apologized for using the word “thugs” to describe those who attack people and destroy businesses.

Hillary Clinton now proposes to end mass incarceration by reducing prison sentences for some drug offenses. She intends to make greater use of “probation and drug diversion programs.”

There are good reasons for decriminalizing drug possession, but Clinton didn’t mention them. Furthermore, Clinton is wrong in believing that decriminalization would end mass incarceration. In 2012, fewer than 7% of inmates at state and federal prisons were in for possessing illegal drugs. And it was rarely just for possession of marijuana. There’s no national data, but state data from Arizona indicates that as few as 0.3% of inmates were incarcerated on account of marijuana possession, and those cases involve people who have been arrested multiple times.

In California, even adding together trafficking or possession offenses, only 1% of state prisoners are incarcerated for marijuana offenses.

To free a larger number of prisoners, you have to include all drug offenses, mainly trafficking. That would cut the prisoner population by 20%.

Clinton claims that putting people in prison for violating parole or minor drug offenses “does little to reduce crime. But it does a lot to tear apart families and communities.”

But virtually no one is in prison for minor drug violations. And there are good reasons for requiring parolees to regularly report to a parole officer, keep their hands off drugs and firearms, and — in some states — take periodic polygraph exams. These rules help keep criminals from committing still more crimes.

Unfortunately, most criminals go on to commit new crimes. Within a year, over 40% of released prisoners are arrested. Within 5 years, 77% of prisoners return to prison.

Does sending someone back to prison “tear apart families”? Sure, but so does sending criminals to prison in the first place. Of course, the victims have also had their families torn apart by murder, rape and theft.

Clinton’s speech raised another reason to release prisoners: the costs of imprisonment. She claims that she can cut the prison population by over 50%. She says, “We would not be less safe.” Perhaps Clinton doesn’t realize that most prisoners are incarcerated for offenses much more serious than marijuana possession.

Myriad academic studies, including my own, show that harsher punishments deter crime. Those states with the largest increases in penalties experienced the sharpest drops in crime rates over the last few decades.

In New York State, it isn’t just a coincidence that violent crimes fell by 60% from 1990 to 2010 at the same time that prison sentence length stays for those crimes more than doubled.

Economists call it the law of demand: Just as lowering the cost of apples means that people will buy more apples, making crime less risky for criminals means that more crime will be committed.

If Clinton wants to reform the system, she might try eliminating mandatory minimum sentences more broadly than she appears to be considering, particularly those that punish people for how they commit a crime rather than for the harm that they do.

Police are by far the single most important factor in reducing crime, but punishment matters, too. Let’s keep the high violent crime rates from the early 1990s a distant memory.

• Lott is the president of the Crime Prevention Research Center and the author of "More Guns, Less Crime" (University of Chicago Press, 2010).