A guard tower is shown at a state prison in California.
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Analysis: The complex history of the controversial 1994 crime bill

When Hillary Clinton and Bernie Sanders take the stage Thursday night in Brooklyn, the debate moderators will almost certainly ask them about a 22-year-old crime law. The issue is back in the news after the 1994 crime bill came up at a Hillary Clinton campaign rally last week.

Since then, much has been said about the legislation’s effect on crime and mass incarceration. Some argue the measure, officially called the Violent Crime Control and Law Enforcement Act of 1994, led to a drop in crime. Others vehemently contend it did not. Questions abound about its impact on mass incarceration.

With millions watching Thursday, the candidates can help put the bill in context — and offer their specific ideas to move criminal justice policy forward.

Like most political compromises, the crime bill did some good and some bad. It contributed to both the crime decline and mass incarceration. But not in the way that people might think.

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First, the good: Though the crime bill was not responsible for the entire drop in crime, it likely helped — not by locking people up, but by putting more cops on the street, studies show. It provided funding for 100,000 new police officers and $14 billion in grants for community-oriented policing, for example. From 1990 to 1999, the number of police officers rose 28 percent, from 699,000 to 899,000, partly funded by the crime bill.

Research also indicates smarter policing tactics, like the ones funded by the bill, and social and economic factors — like an aging population and decreased alcohol consumption — played a role in the crime decline as well.

Crime had already started declining before the bill passed. From 1991 to 1994, crime dropped 10 percent and violence decreased by 5 percent. From 1994 to 2000, crime fell an additional 23 percent, with violent crime dropping by almost 30 percent. All of the above contributed to the fall.

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Then there’s the bad: Although incarceration was already rising steadily before the crime bill, several of its provisions helped increase incarceration even further. Nevertheless, this increase had little impact on America’s subsequent drop in crime.

From 1970 to 1994, the rate of imprisonment exploded 400 percent, to 387 per 100,000 people. From 1994 to 2009, imprisonment continued to rise, doubling.

The crime bill contributed to this increase in incarceration. First, it banned 19 types of semiautomatic assault weapons, authorized the death penalty for dozens of existing and new federal crimes, and instituted a federal “three strikes and you’re out” provision.

But those facets were far less pernicious than how the crime bill influenced states to increase their prison rolls. The bill granted states $12.5 billion to build prisons if they passed “truth-in-sentencing” (TIS) laws, which required inmates to serve at least 85 percent of their sentences.

A 2002 Urban Institute study found that between 1995 and 1999, nine states adopted TIS laws for the first time, and another 21 states changed their TIS laws to comply with the crime bill’s requirements and then apply for funding. By 1999, a total of 42 states had such laws on the books, sustaining an increase in imprisonment.

The crime bill, however, was just the most high-profile legislation to increase the number of people behind bars. On their own, states passed three-strikes laws, enacted mandatory minimums, eliminated parole, and removed judicial discretion in sentencing. By dangling bonus dollars, the crime bill encouraged states to remain on their tough-on-crime course.

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What’s worse, research shows the dramatic increase in incarceration in the 1990s and 2000s played a limited role in bringing down crime. A classic case of “diminishing returns,” incarceration’s effect on reducing crime had been declining since before 1980. Since 2000, the effect of incarceration on crime has been even more limited. When prisons are used sparingly, incarceration is reserved for the highest-risk and most-serious offenders. When prison populations grow to be too large, it is usually by incarcerating less serious offenders. In other words, the more people we put in prison, the less likely each additional inmate has on reducing crime.

With crime and punishment again in the national debate, hopefully Thursday night Sanders and Clinton will outline specific plans for reining in our system of mass incarceration, which imprisons more than 2.2 million Americans. Ted Cruz and John Kasich have also endorsed criminal justice reform in some way on the campaign trail, with even Donald Trump acknowledging possible areas for change.

There is a solution they can champion. Just like in the 1990s, the federal government can encourage states to continue their current trajectory. Between 2008 and 2013, 32 states reduced both imprisonment and crime. A federal “Reverse Crime Bill” can encourage states to go further.

A modern crime bill can shift the flow of federal dollars by providing grants to states that reduce rates of both crime and imprisonment. Clinton, in an interview with the New York Daily News editorial board, recently acknowledged a role for Washington to set financial incentives for states to reduce imprisonment. She should expand on those points in Brooklyn Thursday.

As we debate these issues, it’s important to remember the facts: Crime is at its lowest levels today. And mass incarceration is near its highest. The crime bill likely played a role in the crime decline, but it also certainly increased the number of Americans behind bars.

The next president can and should back legislation to reverse the bad while preserving the good.

Lauren-Brooke Eisen is senior counsel in the Justice Program at the Brennan Center for Justice at NYU School of Law. Inimai Chettiar is director of the Center’s Justice Program.

Policing, Prison and Prison Reform

Analysis: The complex history of the controversial 1994 crime bill