Mr. Leal was arrested in 1994. He was convicted of the rape and murder of a 16 year-old girl. His defenders say this was a miscarriage of justice. They observe that the prosecution used now largely discredited forensic methods. They further claim that he is mentally disabled, had no prior criminal record, and was represented by seemingly incompetent lawyers.
So far there's nothing here to lift this to international attention. And yet, in recent days calls for Gov. Perry to delay the execution have come from U.N. officials as high up as Navi Pillay, the world body's highest defender of human rights. Indeed, the Obama administration has even weighed in, saying the decision to execute Mr. Leal would cause "serious repercussions" and even "irreparable harm" to US foreign relations.
There is one detail in the case that elevates it to this level: Mr. Leal was born in Mexico. His family moved to the States when he was two. Though he graduated from a San Antonio high school, he never obtained citizenship. Consequently, though raised in Texas, he is still officially a citizen of Mexico.
This means, technically, that when he was arrested and his circumstances became apparent, he should have been told that he could seek help from the Mexican consulate in the US. The right to consular assistance for foreign nationals charged in another country is enshrined in a treaty the U.S. ratified in 1969.
Mr. Leal's defenders say had he known this before the trial then consular officials might have secured him more competent attorneys, who could have swung the case the other way.
Certainly, that's how the Mexican government sees things. In 2004 they took the case - along with those of 50 other Mexican nationals in U.S. jails under similar circumstances - to the International Court of Justice. The court found in Mexico's favor and in effect asked for all these cases to be given judicial reviews.
The Bush administration recognized the court's jurisdiction in this matter, and the president signed an Executive Order requesting that American states affected by the ruling comply. Texan authorities have openly flouted this, saying Texas has signed no agreement with the international court, and there is no federal legislation explicitly demanding they abide by its decisions. Sen. Patrick Leahy (D-VT) recently introduced just such a bill into the Senate, but it is still winding its way through the usual tortuous path.
Absent that legislation, both federal and Texan officials say there is nothing to block Mr. Leal's execution on Thursday. Hence the sudden surge of calls in recent days asking that Gov. Perry grant a delay, anticipating an eventual judicial review.
Gov. Perry is, of course, widely tipped as a potential frontrunner for the Republican presidential nomination should he decide to throw his hat in the ring. For Mr. Leal, then, the timing probably couldn't be worse. Kowtowing to international lawyers is not known as a big vote-winner among Republican primary voters.
So, what would be the consequences if the Lone Star State were to go its own way? Perry has already done this once, back in 2008, when he permitted the execution of Jose Ernesto Medellin. This man had been convicted in Texas of a double rape and murder, and was one of the 51 Mexican nationals mentioned in the ICJ ruling. Though there was international outcry, there was no tangible follow-up. The ICJ decided that this was a violation, but also that it could not follow through on it.
Even if the court were to take action, the chances of anything with real teeth coming out of it are - frankly - zero. The ultimate enforcer of ICJ decisions is the U.N. Security Council - a body on which America has a permanent seat and an unbreakable veto.
America's diplomatic relations with Mexico will almost certainly take a hit if Mr. Leal is executed Thursday. However, the movement to save him is largely constructed around the idea that killing him now would endanger Americans abroad. The rationale goes that if America is seen to violate the international treaty, then it will embolden other states to treat Americans arrested in their lands with a cavalier disregard.
A website dedicated to saving Mr. Leal quotes numerous diplomats and other interested parties in support of this argument. One of them is Euna Lee, an American producer at Current TV who was imprisoned by North Korea in 2009. She cites the importance of her access to the Swedish ambassador in Pyongyang, who represents U.S. interests in that cut-off country.
However, the counter-argument holds that international law is not reciprocal. The imperative for other nations to follow its strictures is not suddenly nullified by a handful of high-profile U.S. violations. Meanwhile, the types of countries that would be most emboldened to deprive US citizens of consular access are the usual suspects such as Iran and North Korea, who would likely find some other loophole anyway. For despite Ms. Lee's protestations about the importance of the Swedish ambassador, she was still sentenced to 12 years of hard labor and it took the intervention of former US president Bill Clinton to get her out.
Some legal experts have noted that the treaty was helpful when America took Iran before the court during the 1979 hostage, crisis. However the eventual ruling in America's favor appears to have had minimal impact on the mullahs.
International Law professors and Current TV producers probably aren't going to be voting in the GOP primaries. Looking online at the types of people who may be, the blog "One Old Vet" puts the prevailing sentiment most succinctly: "This is America and Mexican law, as well as other international law, can go straight to hell!" Similarly, a Fox News write-up about the U.N. intervention grins, "Perry apparently doesn't plan to take his cues from the U.N."
So, things look fairly bleak for Mr. Leal. Indeed, one might say that if Perry does delay the execution, thus bowing to international pressure, it could be the clearest sign yet that he's not running for president.