After a nearly two-year standoff between death penalty states and the federal government, the Food and Drug Administration formally blocked shipments of thousands of illegal execution drugs on their way to Texas and Arizona. The move sets up a potential legal battle between death penalty states and the Trump administration.

In 2015, Texas, Arizona, and Nebraska each purchased 1,000 vials of sodium thiopental, an anesthetic now-banned in the United States. The supplier, a man in India named Chris Harris, claimed to be a manufacturer, but a BuzzFeed News investigation raised questions about his claims.

A facility he lists with the DEA turned out to be a former apartment he left owing rent on. The facility he registered with the FDA is a small office space he rents; a secretary at the building said manufacturing couldn’t be done there.

States, desperate to obtain execution drugs, have turned to Harris a handful of times over the past several years. Each time, Harris convinces the states that the legal problems with the drugs he sells are solved; They’ve never actually been used in executions, but he’s made more than $100,000 from the sales.

In 2015, the FDA warned Texas, Arizona, and Nebraska that buying thiopental from Harris would be illegal, and that they would block the shipments if they tried it.

In the letters, the FDA pointed to a 2012 injunction by a federal judge that forces the FDA to block illegal shipments of sodium thiopental. The ruling came about after the FDA, under President Obama, had allowed shipments of execution drugs into the country.

Inmates sued the FDA, and Judge Richard Leon ruled the government had “a mandatory obligation … to refuse to admit the misbranded and unapproved drug, thiopental, into the United States.” The order also directed the FDA to stop “permitting the entry of, or releasing any future shipments of, foreign manufactured thiopental that appears to be misbranded or [an unapproved new drug].” The ruling was upheld by a federal appeals court in 2013.

Despite the FDA's warning that doing so would be illegal, the states tried to import the drugs anyway.

Harris shipped the drugs to Nebraska, Texas and Arizona last year. Nebraska’s shipment never left India; the state tried to get a refund, but Harris refused. Texas and Arizona’s shipments were seized at the airport by Customs and Border Patrol, under orders from the FDA.

Since then, the states hired a former FDA investigator and a well-connected law firm to try to convince the federal government to allow the drugs into the country.

In January, Texas sued the FDA for detaining the drugs without making a final decision, prompting the FDA to agree to provide one in April. Both Texas and Arizona have publicly indicated that they intend to sue the FDA if the drugs were formally denied.

The deadline for making the final decision was Thursday. The Justice Department announced the decision in a court filing on Thursday afternoon.

"[T]he United States Food and Drug Administration (FDA) has issued a final decision, refusing admission of the detained drugs into the United States," the lawyers wrote.

In a statement, the FDA said the drugs would now have to be sent back to the supplier or destroyed, adding that its hands were tied because of an injunction put in place years ago.

"The FDA previously exercised enforcement discretion regarding the importation of sodium thiopental used for lethal injection," FDA spokesperson Lyndsay Meyer said in a statement.

"However, in 2012 the United States District Court for the District of Columbia issued an order that permanently enjoins the agency from" allowing foreign thiopental that appears to violate federal law.

"As such, the court order requires the FDA to refuse admission to the U.S. any shipment of foreign manufactured sodium thiopental being offered for importation that appears to be an unapproved new drug or a misbranded drug."

In a statement, the Texas Department of Criminal Justice criticized the decision to block the drugs.

"It has taken almost two years for the Food and Drug Administration to reach a decision which we believe is flawed," TDCJ spokesperson Jason Clark said.

"TDCJ fully complied with the steps necessary to lawfully import the shipment. We are exploring all options to remedy the unjustified seizure."

Before Texas purchased drugs from Harris, the state had intended to purchase the drugs from a different supplier in India. The deal fell through when the supplier was raided by India’s Narcotics Control Bureau, its facility shut down, its drugs seized, and five of its employees arrested. Indian authorities say the company was selling opioids and psychotropic drugs illegally to people in the United States and Europe.

Weeks later, Texas turned to Harris and sent him a check for $25,000.

In total, the three states sent Harris more than $75,000. If Texas and Arizona are hoping to get a refund, they are unlikely to get it. Nebraska asked for one last year and the supplier refused.

“I am sorry to state that refund of the payment is not possible as there has been no fault of my company,” Harris wrote, adding that he hoped they could do business again in the future.