In 1997, Gov. George Pataki of New York wrote an opinion piece for USA Today making the case for one of his key policy priorities. "In New York," he wrote, "the death penalty has turned the tables on fear and put it back where it belongs -- in the hearts of criminals. Within just one year, the death penalty helped produce a dramatic drop in violent crime." The "short year" he refers to was 1995 to 1996. When he took office in 1995, he signed a law reinstating the death penalty. That year, New York's violent crime rate was 84.2 per 10,000 residents. By 1996, it was down to 72.7. And by 2006, when he left office, the rate had fallen to 43.5 -- nearly cut in half.

But it is not that easy.

On Thursday, the Death Penalty Information Center announced that executions under the death penalty are at a 20 year low. Not since 1994 have as few prisoners been put to death, the reasons for which are complicated and outlined nicely here.

Put into visual form, the curve (mountain range?) looks like this.

You'll notice that we left a lot of space to the left of that graph. Executions were banned by the Supreme Court from 1972 to 1977, which is why the data begins then. DPIC doesn't offer data prior to that point, but even before the Supreme Court changed its mind, executions had tapered off. (As, happily, had illegal lynchings.)

The reason we left that space there was to address Pataki's other point: crime.

The early 1990s were a time in which the United States saw record-high crime. It's easily visible on this graph, which uses violent crime rate data from the FBI. Crime rose steadily from 1960 to 1991, at which point it began sliding downward again.

Notice two things. First: The increase in executions trails the decrease in violent crime by eight years -- with the former peaking in 1999. Some might argue that eight years is about how long it takes for a case to wend its way through the courts and result in an execution. But that doesn't address the second point: Why, if the death penalty is a deterrent, has the crime rate not gone back up?

Even in Texas, the state perhaps best known for its use of the death penalty, a dip in usage hasn't resulted in more crime.

There are a lot of theories about why the crime rate went down so quickly, and we mean that literally. Police tactics, leaded gasoline, abortion, the fade-out of the Boomers: all have been considered.

It seems hard to argue, 17 years after Pataki wrote his essay, that the death penalty played much of a role in it. After all, New York's death penalty law was thrown out in 2004, but crime kept dropping.

And now the kicker: It was dropping before the death penalty went into effect, too -- before Pataki ever signed the law in the first place. In 1991, New York's crime rate was 116 per 10,000 people. In 1995, it had already fallen to 84.2, as we mentioned earlier. In 2012, it was 40.1.