The unseemly love affair of some American politicians with the death penalty is bad for justice and bad for our country's standing in the world. It inflicts a wholly unnecessary moral stain on a nation that rightly preaches the rule of law to everyone else.

Even more remarkable is the indifference that five justices of the Supreme Court have shown to such considerations.

And then there is Gov. Rick Perry of Texas, who insisted upon pushing ahead with the execution of Humberto Leal, a Mexican national convicted of the rape and killing of a teenager. Even former President George W. Bush -- who presided over 152 executions as Perry's predecessor -- had qualms about the case. Bush hasn't gone soft. He's legitimately worried about the costs of the United States thumbing its nose at the government of Mexico and the world.

President Obama, the International Court of Justice and the Mexican government all wanted a stay of execution. But Perry's press secretary was unapologetic. "Texas," said Katherine Cesinger, "is not bound by a foreign court's ruling."

Imagine if an American life was at stake and a press secretary said that Iran -- or Russia or Saudi Arabia or China -- did not feel "bound by a foreign court's ruling."

Let's be clear: This case involved a brutal crime, and Leal himself seemed to confess his guilt just before he died. "I take full blame for everything," he said. "I am sorry for what I did."

No one disputes that Leal deserved to be punished. And while I am strongly opposed to the death penalty, I would stipulate that if a state chooses to have one, this is the sort of crime for which it was intended.

But the episode dramatizes the way in which these inevitably politicized death penalty cases seem to harden us and rob us of our reason.

The International Court of Justice ruled that 51 Mexican-born inmates nationwide, including Leal, were entitled to new hearings in American courts to determine if their consular rights were violated. President Bush accepted the decision, but the Supreme Court overruled him in 2005.

So Sen. Pat Leahy has been pushing -- so far unsuccessfully -- to change American law to comply with the Vienna Convention on Consular Relations. He argues that "thousands of Americans are detained abroad while they study, travel, work, and serve in the military" and need access to consular officials who can "monitor their treatment, help them obtain legal assistance, and connect them to family back home." The Vienna Convention, which the United States agreed to, protects such rights, Leahy noted. The four more liberal justices on the Supreme Court thought that little would be lost by delaying the execution, perhaps only until the end of the summer.

But the five-justice conservative majority let the execution go forward last week. They dismissed the president's worries about the impact of the execution abroad as "free-ranging assertions of foreign policy consequences" that were "unaccompanied by a persuasive legal claim." Those who oppose the death penalty or think it's imposed too frequently find ourselves interceding in cases involving truly terrible crimes that deserve severe punishment. But this is not about absolving criminals. It's about our nation's core values and how the rest of the world sees us. In this instance, it's also about protecting the rights of Americans overseas.

When it comes to capital punishment, can't we find it in ourselves as a nation to let our reason check our passions, even when those passions are entirely understandable?