Eugenics is alive and well in Tennessee.

This spring, Judge Sam Benningfield approved a program in which prisoners at the White County Jail in Sparta were offered reproductive sterilization in exchange for reduced sentences. As of May 15, more than two dozen women had reportedly agreed to birth-control implants and 38 men to vasectomies.

Sterilizations to lessen criminal sentences are not a new phenomenon in Tennessee. Between 2010 and 2015, they were offered as part of plea deals in four criminal cases.

To put these sterilizations in perspective, we need to go back to the beginning.

In 1866, an Augustine monk named Gregor Mendel found that when he crossed pea plants, certain physical traits like plant size and leaf color dominated. Mendel proposed that pea plants were inheriting one “factor” from each parent. Today we call these “factors” genes.

A few years after Mendel published his findings, a British scientist named Francis Galton—who was a half-cousin of Charles Darwin—made the leap from peas to people and from physical traits to something broader. If we could breed better animals, reasoned Galton, couldn’t we breed better humans, too? Wouldn’t traits like intelligence, loyalty, bravery, and honesty also be inherited? And wouldn’t selecting for these traits make for a better world? One free from drunkenness, violence, and poverty. A world, he proposed, where the lower classes could be bred out of existence, no longer a burden to society. He called his plan eugenics, from the Greek for “well born.”

In the early 1900s, this ideology crossed the ocean and landed in a small cove near Huntington, New York. The two men who championed Galton’s cause were Charles Davenport and Harry Laughlin. “As [society] claims the right to deprive the murderer of his life,” said Davenport, “so also it may annihilate the hideous serpent of hopelessly vicious protoplasm.”

Davenport and Laughlin’s list of “vicious protoplasm” included the “feeble-minded,” the poor, alcoholics, criminals, epileptics, the insane, the “constitutionally weak,” those suffering from venereal diseases, the deformed, and those deaf, blind, or mute.

In October 1910, their Eugenics Records Office opened for business. Its mission was clear: Determine which Americans were of inferior stock and prevent them from marrying or having children. The first step was to confine them to unisex institutions for the insane or mentally disabled. The next was to sterilize those who were still roaming free.

The eugenicists had completely bastardized Mendel’s laws. While physical characteristics such as eye color can be mapped to specific genes, traits like criminality, alcoholism, or susceptibility to venereal diseases can’t. Not everything can be accounted for by strict Mendelian genetics.

Nonetheless, the false notion that selective breeding could make for a better society allowed Americans to cloak some of their worst prejudices in the gilded robes of science.

The zealous efforts of Davenport and Laughlin shaped a nation.

By 1928, about 400 colleges and universities in the U.S. offered courses in eugenics, and 70 percent of high-school biology textbooks embraced the pseudoscience. The eugenics movement also changed the law: Four states prohibited the marriage of alcoholics, 17 banned the marriage of epileptics, and 41 forbade the marriage of the feeble-minded and the insane. By the mid-1930s, America was the world leader in banned marriages. (Marriage-restriction laws weren’t declared unconstitutional until 1967.)

American citizens were now ready to take the next step—to legislate forced sterilization. When the dust settled, 65,370 poor, syphilitic, feeble-minded, insane, alcoholic, deformed, lawbreaking, or epileptic Americans in 32 states had been sterilized. California alone had more than 20,000. Few rose in protest. It was one of the darkest moments in American history.

Most of those sterilized didn’t understand what was being done, and were surprised that they could no longer have children. Some were told they were having a different surgical procedure. (Because of its popularity in the South, sterilizations were often referred to as “Mississippi appendectomies.”) Others were told to sign a form that they couldn’t read. In 1927, civil libertarians were delighted when the U.S. Supreme Court agreed to hear the case of a woman who was being sterilized against her will. At last, the most disenfranchised members of society would have their day in court. The person who was being sterilized was Carrie Buck. The doctor who was to perform the sterilization was John Bell.

The associate justice who wrote the opinion for the majority was Oliver Wendell Holmes, Jr. A proud defender of the Constitution and individual liberties, Holmes had authored nearly a thousand valued opinions.

On May 2, 1927, justices ruled 8-1 in favor of Carrie Buck’s sterilization. Holmes wrote, “Carrie Buck is a feeble-minded white woman. She is the daughter of a feeble-minded mother in the same institution, and the mother of an illegitimate feeble-minded child. It is better for all the world, if instead of waiting to execute degenerate offspring for crimes, or to let them starve for their imbecility, society can prevent those who are manifestly unfit from continuing their kind.” Then Holmes authored the words that placed Buck v. Bell in the pantheon of America’s most embarrassing Supreme Court decisions: “Three generations of imbeciles are enough,” he wrote, effectively solidifying laws that even the most ardent eugenicists thought were unenforceable. One critic later wrote that Holmes’s opinion represented “the highest ratio of injustice per word ever signed on by eight Supreme Court justices.”

On Oct. 19, 1927, her legal options exhausted, Carrie Buck was sterilized; she thought she was having an appendectomy.

In 1933, the year that he came to power, Adolf Hitler passed the Law for the Prevention of Hereditarily Diseased Offspring. The list of those to be sterilized was virtually identical to that first generated by the Eugenics Records Office in Cold Spring Harbor. Clinics were established and doctors were fined if they didn’t comply with the law.

Within a year, 56,000 Germans had been sterilized; by 1935, 73,000; by 1939, 400,000, logarithmically dwarfing the number of sterilizations performed in the U.S. The procedure was so common that it had a nickname: Hitlerschnitte, “Hitler’s cut.” Americans took note. Joseph DeJarnette, superintendent of Virginia’s Western State Hospital, lamented, “Hitler is beating us at our own game!”

Twenty years later, Buck v. Bell would be presented in support of SS officer Otto Hofmann during the Nuremberg military tribunal investigating Nazi war crimes.

The U.S. Supreme Court has never officially overturned its verdict.

Paul A. Offit is a professor of pediatrics and director of the Vaccine Education Center at the Children’s Hospital of Philadelphia. He is the author of Pandora’s Lab: Seven Stories of Science Gone Wrong (National Geographic Press).