Worldwide use of the death penalty rose sharply last year, with 2015 tallying the highest number of executions in 25 years, according to a report released Tuesday by Amnesty International.
At least 1,634 people were executed last year, according to available data as well as executions corroborated by the international human rights group.
The number, which is more than double the 2014 total, is a conservative estimate: Countries currently in conflict, like Syria, were not included since their data could not be corroborated, nor were specific numbers from China, where such data is considered a state secret. China alone is believed to carry out executions that annually number in the thousands.
“The rise in executions last year is profoundly disturbing," Amnesty International’s Secretary Salil Shetty said in a statement. "Not for the last 25 years have so many people been put to death by states around the world."
Despite the high rate of global executions last year, the number of countries that have the death penalty is growing smaller by the year. Fiji, Madagascar, the Republic of Congo and Suriname all abolished the death penalty in 2015, while Mongolia's abolition takes effect on July 1.
At least 60 other countries that still have the death penalty but have not used it in a decade are what the United Nations considers "de facto abolitionists."
The seemingly opposite trends -- a 25-year record high of executions, and an ever-shrinking number of countries that perform them -- hinge on just a few countries that carry out executions at a disproportionately high rate, according to Robert Dunham, executive director of the Death Penalty Information Center.
"Globally, you’re seeing generally reduced use of the death penalty except countries like the four major outliers — China, Pakistan, Iran and Saudi Arabia," Dunham said.
Just three countries -- Iran, Pakistan and Saudi Arabia -- are responsible for nearly 90 percent of all executions that Amnesty International recorded last year.
Iran led with at least 977 confirmed executions, mostly by hanging (though Amnesty International believes there were more) -- 58 of which were held in public.
Pakistan's 326 executions was the highest figure Amnesty International said it has ever recorded for the country; it notes the surge comes in the year following a lifting of a six-year-old moratorium on executions.
Saudi Arabia, where executions were up 76 percent from last year, had at least 158 confirmed executions, mostly by beheading.
The country that ranks fifth for the most executions worldwide (including China as the presumed leader): the United States.
The U.S. had 28 executions last year, the lowest number since the early 1990s.
Amnesty International notes that for the first time since the death penalty was reinstated in the 1970s, more than half of states have abandoned the death penalty in either "policy or practice": 18 U.S. states have abolished or repealed the death penalty, while nine more have not had executions in at least a decade.
Dunham said trends with the U.S. penalty system are in some ways a microcosm of what's happening worldwide. “Just as most of the United States is moving away from the death penalty and most of the world is moving away from the death penalty, there are concentrated pockets of where we see outlier practices."
Domestically, three states — Texas, Missouri and Georgia — carried out 86 percent of all the executions in 2015. Add Florida, and the four states accounted for 93 percent of all U.S. executions last year.
Rick Halperin, a human rights and death penalty expert from Southern Methodist University, noted that high rates of execution are partly explained by unfair trials and the low threshold in countries like Iran and Saudi Arabia: People there are executed for supposed crimes like drug trafficking, adultery, blasphemy and homosexuality.
And while Americans may balk at such actions being punished by death, Halperin notes the U.S. has been sluggish on bringing its capital punishment system in alignment with international law.
It wasn't until 2002 that the U.S. stopped allowing the execution of people with intellectual disabilities, and it wasn't until 2005 that the execution of juveniles (or those who committed a crime as a juvenile) was ruled unconstitutional. Up until 2008, some states were considering crimes other than murder a capital offense.
"No matter how 'good' a country’s human rights record is, if it’s killing people in the name of the law, it can’t have a good human rights record,” Halperin said.
Amnesty International notes that a significant number of executions -- including those in the U.S. -- run afoul of international law.
"Amnesty criticizes the U.S. for its violation of human rights treaties. Despite the constitutional prohibition against executing people with intellectual disabilities and people who have become mentally incompetent, the U.S. still carries out executions of individuals that fall within those categories,” Dunham said, citing the 2015 execution of Virginia murderer Alfredo Prieto, whom Dunham notes was also a foreign national.
Both Halperin and Dunham said countries that break international treaties with regard to the death penalty and human rights -- including the treatment of condemned inmates -- do so with impunity. Bodies like the U.N. have no mechanism to sanction countries committing the violations and can do little more than publicly chastise them.
The international community's ability to pressure countries is significantly undermined by the U.S.'s own track record, Dunham notes.
"When you look at whose company we’re keeping, it is a group of countries who are not known for their adherence to and promotion of human rights," he said. Dunham noted that in Belarus, the only European nation to still have the death penalty, capital punishment advocates have cited the U.S.'s ongoing system as justification of their own.
Halperin, who opposes the death penalty, said U.S. abolition would have "profound ramifications for the rest of the world."
"Smaller countries that talk about reintroducing it, like Guatemala or the Philippines, can still use the argument that we have it," he said. "In a pure human rights context, it would finally put the U.S. on a higher moral plane. While we have other human rights problems, we wouldn't have this central problem of the death penalty."