On Tuesday night, the state of Texas executed Miguel Paredes by lethal injection for murdering three members of a rival gang* sixteen years ago. With no executions scheduled by the state department of criminal justice for November or December, Paredes' death marks the tenth and final execution for Texas this year—the fewest in almost two decades.

2014 wasn't anomalous either. Executions in Texas, the most prolific death-penalty state in the country, spiked after Congress restricted federal appeals in death-penalty cases with the Antiterrorism and Effective Death Penalty Act in 1996. Since then, however, the death penalty has been in overall decline both in Texas and nationwide. Thirty people have been executed so far this year in the entire United States, whereas Texas alone executed 40 people at its peak in 2000.

What's driving the decline? Since executions peaked nationally in the late 1990s, multiple Supreme Court rulings have limited the death penalty's scope and application. The justices barred executions of the mentally disabled in Atkins v. Virginia in 2002, for example, and eliminated the death penalty for individual crimes other than first-degree murder in their 2008 decision in Kennedy v. Louisiana. (In the latter case, the court expressly left the death penalty intact for so-called crimes against the state—treason, espionage, terrorism, and "drug kingpin activity"—without ruling on the constitutionality thereof.) This resulted in fewer cases with which the death penalty could be applied, while also imposing new legal hurdles before it could be carried out.

But for Texas, the greatest shift came in 2005. First, the Supreme Court ruled in Roper v. Simmons that executing defendants who were minors when they committed the crime violated the Eighth Amendment. Texas had led the nation in imposing the death penalty on under-18 defendants prior to Roper; 29 inmates had their sentences reduced accordingly after the ruling. More inmates left Texas' death row alive than dead that year for the first time since 1989. At the same time, legislators gave Texas juries the option to sentence murder defendants to life without parole, thereby lowering the number of new death-penalty convictions.

Other extrajudicial factors are also slowing down the death penalty in Texas and around the United States. Thanks to a European Union embargo that bars the sale of lethal-injection drugs to the U.S., executions nationwide have slowed precipitously as states scramble to find replacements and substitutes. The few companies willing to provide the drugs are also feeling the impact: After Mylan provided Alabama with the paralytic drug rercuronium bromide, a German investment firm divested $70 million from the U.S. drug manufacturer earlier this month.

This doesn't mean executions will completely halt any time soon in Texas. State officials say they have a sufficient supply of pentobarbital for upcoming executions thanks to a secret supplier they refuse to name through 2015. Six in 10 Americans still support the death penalty according to a recent Gallup poll, and Greg Abbott, who will likely be elected governor of Texas next week, is also a staunch proponent.

Reversing the overall downward trend, however, would require either a drastic shift in the Supreme Court's jurisprudence or a complete overhaul of Texas sentencing law. Neither are imminent.

* = This post originally stated Paredes had been executed for murdering a woman and her two children. We regret the error.