Lethal injection, which became the death penalty method of choice after the electric chair was deemed too cruel, is now falling out of favor.

Drug companies are rebelling against it. States are fighting to keep it. And there is a new wave of controversy – and a slew of lawsuits – alleging that lethal injections are almost as inhumane as firing squads.

Now the future of legal injection is uncertain, and states find themselves looking for alternatives.

There are 31 states that currently allow the death penalty, with lethal injection being the primary method to carry out the practice. In recent years, many of those states have faced drug shortages due to manufacturers cutting off the supply due to objections over how their drugs are used.

Robert Dunham, director of the Washington, D.C.-based Death Penalty Information Center says he’s not surprised that drug supplies are being cut off.

“In every state that’s attempting to carry out executions, prisoners have been challenging the method of execution. And those challenges have either been to the entire state’s protocol where they are attacking the use of particular drugs, or it’s been what’s called an as-applied challenge when people who have particular medical conditions say that the use of any kind of lethal injection is inappropriate for them because of the way they’re likely to respond.”

Several states including Alabama, Arkansas, Louisiana, Mississippi, Missouri, Nevada, Nebraska, Ohio, Tennessee and Texas have recently faced court challenges or inquires over lethal injection protocols, according to the Death Penalty Information Center. A judge in Tennessee recently granted the state permission to begin using a new cocktail of drugs to carry out executions.

Some states have even gone further to enact secrecy laws to protect the source of acquired drugs.

“All of the states that have been carrying out executions have some form of secrecy...” Dunham said. “The states initially said that this is necessary for them to obtain the drugs because drug manufacturers were being harassed, they claimed, by anti-death penalty advocates. Those allegations have all turned out to be false. But the states have continued to attempt to expand secrecy and the real reason is because the drug manufacturers themselves are opposed to the use of their medicines in executions.”

Drug manufactures such as Pfizer, Athenex, Akorn, Roche, Janssen and others have put out statements opposing the use of their products in executions. In 2016, Pfizer started imposing controls over its medicines to make sure they would not be used for lethal injection.

Drugs like Midazolam and Pentobarbital have been affected by companies unwilling to sell their products to states. Midazolam was at the center of controversy after a botched attempted execution of an Oklahoma inmate in 2014. The drug was also part of an intense execution schedule and method carried out by the state of Arkansas last year.

Dunham also discussed a February 2017 attempted execution involving an Alabama inmate where the man was stuck about 12 times in order to find a usable vein. The prisoner’s attorney said the man’s bladder may have been punctured during the attempt.

In a more recent case, the United States Supreme Court stayed the execution of Missouri death row inmate Russell Bucklew. Bucklew has cavernous hemangioma, which includes symptoms such as weak blood vessels and blood-filled tumors in the throat and nose.

One doctor and professor of medicine says the act of lethal injection is often confused for a medical procedure.

“These are the sorts of medications that doctors use and how these medications are used for the purposes of execution, that’s not really a doctor’s job,” said Dr. Joel Zivot, an associate professor of anesthesiology and surgery at Emory University Hospital in Atlanta. “That’s the state taking these sorts of medications and repurposing them as poison. In my hand, these are used to treat diseases and in the state’s hand the same compounds are now used to kill.”

Zivot strongly stated that he’s not an advocate or opponent of the death penalty itself but rather a campaigner for the elimination of the field of medicine from the entire process of executing criminals. He noted how some instances of the practice could violate the Eight Amendment. Zivot is not alone, the American Board of Anesthesiology and the American Medical Association forbid members from participating in executions.

Some states have sought different executions methods if lethal injection drugs are not available. Alabama, Oklahoma and Mississippi all have laws that allow the use of death by nitrogen hypoxia, or gas chamber. Tennessee allows the use of the electric chair while Utah has passed a law allowing death by firing squad if the state is unable to obtain the proper drugs. New Hampshire allows inmates to be executed by hanging if it becomes impractical to carry out a death sentence by injection.

Criminal defense attorney Ashleigh Merchant said states may have to go as far as producing their own drugs to carry out the death penalty. Merchant went even further to say that death by lethal injection could come to a stop.

“I do think this issue could go to the Supreme Court, ultimately, but it’s a very interesting issue that the courts are probably not going to be able to resolve because what we’ve got is independent drug manufacturers who are refusing to make the drugs unless the state says they’re not going to use them for executions,” Merchant said. “Now we’ve got drug companies that say we don’t’ believe in the death penalty and they can’t be forced to produce drugs that are going to be used in executions. So they’re really exercising their right to free speech and their belief system and that may put an end to this type of execution.”

Merchant said death penalty procedures like the electric chair and hanging became obsolete with societal pressures.

“I think it’s more than just the individual inmate’s rights. I think it’s us as a society because the Supreme Court said that we can have the death penalty but it has to be judged by an evolving standard of decency,” she said. “Yes, we want finality in these sentences but is there a way to do that without violating the Eighth Amendment and without being cruel and unusual and we just haven’t been able to find a method that society is OK with.”