Nicholas Jones didn’t think twice about purchasing a lithium-ion battery from Amazon in 2016. Like most Americans, he was used to ordering whatever he needed on the site and having it show up at his front door days later. So when his laptop’s battery stopped working, Jones, then a graduate student, went online, found a replacement HP battery for about $15, and bought it.

A few nights later, he was sitting on the couch in his Buffalo, New York, apartment when he heard a sound like a gunshot. His fiancée screamed. The lithium-ion battery in the laptop sitting next to him had ignited, setting his couch on fire. Battery cells were flying all over the living room, leaking acid. “It was like a war zone,” Jones told me. Later, he was treated for first-degree and chemical burns. His computer and hardwood floor were destroyed.

Curious about what had happened, Jones went back online to try to contact the seller and alert Amazon to the problem. Scrolling through reviews, he realized other buyers were reporting fires from the same item. But Amazon seemed unconcerned, he told me: Customer-service representatives treated his report like a new one each time he called, asking for his name, the order number, and the story of what had happened over and over again. Amazon would not put him in touch with the seller and never assumed blame for the fire.

“They weren’t even like, ‘We’ll get to the bottom of it,’” he told me. “It was, ‘We’ll put you on hold for 45 minutes until you get annoyed and hang up.’” He eventually stopped trying for a response; he was in the middle of an exam period and had other things on his mind. “I was a little naive. I thought, This billion-dollar entity—they’ll at least cover my losses. What did I really expect? It is a big company, and they treated me like a big company.” (Amazon declined to answer specific questions about Jones’s allegations.)

Jones had unwittingly collided with one of e-commerce’s strangest and most vexing truths: In the massive global network of manufacturers, distributors, sellers, and resellers, it can be nearly impossible to tell who’s actually responsible for getting any given product into your living room. Even when it sets your couch on fire.

The battery that exploded on Jones was a lithium-ion cell, a type that’s highly efficient, increasingly common, and, as it turns out, occasionally flammable when overheated or punctured. Poor design can heighten the risk—a particular danger as companies race to pack more and more power into smaller batteries and cheaper devices. “When you are pushing a battery to its limits,” said Nadim Maluf, the CEO of the battery-software company Qnovo, “the margin of error is extremely thin.”

The inherent economics of the battery industry make things even worse. Many lithium-ion batteries are produced in China—where it can be difficult to monitor what materials are used and whether corners have been cut in the manufacturing process—and by companies that are working quickly to avoid copycats, which can lead to unclear instructions and botched construction. “We are seeing a ton of batteries manufactured in China that are terribly made, completely unsafe … rushed to be placed on the market,” said Greg Bentley, an attorney who has worked on more than 20 lithium-ion explosion cases. Many shoddily made batteries are also counterfeit, meaning they bear the name of a trusted brand even if they were made by an entirely different company.

“It’s really a perfect storm for potential hazards,” Maluf said.

An untold number of lithium-ion-battery incidents go unreported, and no one agency tracks them. But the U.S. Fire Administration declared the batteries the “root cause” of at least 195 separate fires and explosions from 2009 to 2017. The Federal Aviation Administration has reported a few hundred incidents of smoke, fire, extreme heat, or explosions involving lithium-ion or unknown batteries in flight cargo or passenger baggage. And there were 49 recalls of high-energy-density batteries from 2012 to 2017, according to the Consumer Product Safety Commission, concerning more than 4 million devices, including mobile phones, scooters, power tools, and laptops.

In 2016, David Jarrett, a student at Rowan University, suffered first-, second-, and third-degree burns after a portable phone combusted in his pocket, according to a complaint filed in New Jersey federal court. In 2017, the lithium-ion battery that Kyle Melone had bought for his vape pen on Amazon exploded in his pocket, setting his shorts and leg on fire; he ended up in the intensive-care unit, according to a complaint filed in Rhode Island federal court. Exploding lithium-ion batteries have caused hoverboards to catch fire and houses to burn down; Bentley told me his clients include a man who lost an eye, another who burned his genitals, and one who experienced “massive brain injury.”

The link among many of these dangerous products is Amazon, where the world shops. More than half of the items sold on Amazon are listed by third-party sellers—not by Amazon itself—which makes ensuring that products are safe and authentic difficult, according to Juozas Kaziukenas, the founder of Marketplace Pulse, a firm that researches Amazon. In the case of batteries, batches of lithium-ion cells made in China that don’t pass inspection sometimes end up listed by sellers on Amazon, said Michael Rohwer, a director of Business for Social Responsibility, a nonprofit that works with companies on their supply-chain practices.

In a statement, an Amazon spokesperson said, “Safety is important to Amazon and we want customers to shop with confidence on our stores. Third-party sellers are required to comply with all relevant laws and regulations when listing items for sale in our stores. When sellers don’t comply with our terms, we work quickly to take action on behalf of customers.”

Read: Amazon may have a counterfeit problem

Insurance companies have even started to sue both Amazon and battery makers because they say they’ve had to pay out many claims over lithium-ion-battery explosions. Allstate New Jersey Insurance sued Amazon in U.S. District Court in New Jersey, alleging that a battery bought on Amazon caused “extensive” damage to a home, which required the insurance company to make “significant payments” to the insured. That case was eventually dismissed, but both State Farm and General Insurance Company of America are currently suing Amazon because of fires they say were caused by lithium-ion batteries purchased on the platform. (Amazon declined to discuss any of these specific cases, but has denied the allegations in court filings, saying it was not the seller of these products.)

Even as the fires keep happening, battery manufacturers, Amazon, and consumers are all blaming one another. But so far, courts have pinned the blame neither on Amazon nor on the battery manufacturers. This is because websites such as Amazon can argue in court that they are merely a platform that allows buyers and sellers to connect. Unlike, say, Macy’s, which buys products wholesale and resells them to consumers, Amazon often doesn’t own or even touch the products bought and sold on its site—so in Amazon’s view, it’s not liable for defective products. In its response to David Jarrett’s legal complaint, the company said in a court filing that his alleged injuries “were caused by acts or omissions of third-persons or entities over which Amazon has no control.” And it’s easy for third-party retailers to disappear after selling a defective or dangerous product, even if they pop up a few weeks later under a different name and address, again selling dangerous products.

Battery makers, meanwhile, place the blame on consumers, for buying the things in the first place. George Kerchner is the executive director of the Portable Rechargeable Battery Association, which represents manufacturers. He argues that consumers simply should not be handling many types of lithium-ion batteries—particularly the 18650, which is slightly larger than a AA battery and is one of the most commonly problematic lithium-ion batteries—themselves. “If someone is using a lithium-ion battery for something other than which it was designed,” he said, “that’s out of the control of manufacturers.” Consumers simply should not be able to walk into a retail store and find a 18650 battery, Kerchner told me. But Bentley, the attorney, told me his customers have bought individual lithium-ion batteries from brick-and-mortar stores, websites, and other people.

Kerchner suggested that the real enemy is e-cigarette manufacturers, which have designed devices around 18650 cells. In November, LG Chem, the Korean company that makes LG-branded lithium-ion batteries, sent a letter to sellers and distributors of e-cigarette devices and equipment, telling them, “Individual consumer use and handling of 18650 cells is a dangerous misuse of the cells that can lead to severe burns and disfigurement.” It asked companies to stop selling LG 18650 cells, and to tell customers who had bought the cells in the past that they should dispose of them safely. (A Samsung spokesman directed me to a product page that warned consumers against charging individual cylindrical lithium-ion batteries. Sony directed me to a website warning customers that using cylindrical lithium-ion batteries in vape pens “may cause a serious risk to personal property and safety,” and that Sony does not intend for them to be used that way.)

But can consumers really be blamed for buying readily available batteries that extend the life of their products? Kyle Wiens, a co-founder of iFixit, which provides tips on how to repair devices, said the answer is no. “It’s so condescending to put the blame on the user and say, ‘We made this thing and then they used it wrong, and that’s why they got hurt,’” he told me.

Last year, the FTC sent warning letters to six major companies, saying it may be illegal to tell consumers that their warranties will be voided if they remove or replace a specific part. Blaming consumers for replacing batteries is like blaming car owners for replacing their tires, Wiens said—it’s unfair to expect consumers not to try to extend the life of their products. If users can’t replace dead batteries, the products will quickly reach the end of their useful life and end up in a landfill. (And then the lithium-ion batteries can cause waste-management facilities to catch fire and burn down, as happened at a materials-recovery site in San Carlos, California.)

The problem, Wiens said, is that it’s incredibly easy to buy poorly made batteries and have absolutely no idea that they may be dangerous. This is partly because you can buy almost anything on Amazon, including counterfeit and dangerous goods.

Read: The problem with buying cheap stuff online

Many Amazon sellers reported receiving emails last August saying Amazon had prohibited the sale of cylindrical-lithium-ion batteries, including the 18650—but in February, I bought eight of them there. I also found a number of listings for 18650s accompanied by old reviews reporting problems with some of the batteries listed. One had a review from June 2018 saying the battery started smoking and melted the customer’s battery coil; another had a review from September 2018 reporting that the charger caught fire. Both products were still on sale as of January 2019. A review of a 18650 battery on Amazon from February 2018 read: “This product will EXPLODE!!!” and included pictures of a charred charger and burned floor; the product was still listed as of January 2019.

When I contacted Amazon on March 5, asking the company why I was able to purchase lithium-ion batteries on the site if they were banned, a spokeswoman told me that the 18650 batteries were indeed prohibited and that she would have her team “look into it.” Three days later, almost all the listings were gone, and the company told me in a statement that “the product in question has been removed.” About a week after that, just a few listings for 18650 batteries remained on Amazon, including two tagged by Amazon as “best sellers.” One of those listings had numerous reviews from users warning others that they were nowhere near as powerful as advertised. “AVOID … Specification is a lie; may be a fire hazard,” one review read. When I searched again in April, I found yet more 18650 batteries for sale.

Generally, Amazon has been slow to take down products that are alleged to be dangerous, copyright-infringing, or counterfeit, even after being alerted to a problem. “It’s quite often that enforcement of policies and the creation of policies are very different things on Amazon,” Kaziukenas told me.

Amazon knew there was a chance the battery would explode in the hoverboard Megan Fox bought in late 2015, Fox and her husband, Brian, alleged in a lawsuit. In a deposition, Damon Jones, an Amazon executive, established that Amazon had a product-safety team of 10 employees who monitored social media for product-safety problems, according to an appeal the Foxes filed in the Sixth Circuit Court of Appeals. (The appeal seeks to overturn the 2018 ruling by a federal judge in Tennessee that Amazon was not liable for the family’s house fire.) The Amazon team, working from November 2015 to January 2016, found 17 hoverboard fires and explosions in the United States, according to emails cited in the complaint; Amazon then required employees to work the day after Christmas to monitor hoverboard safety issues, according to the appeal. Amazon did suspend hoverboard sales on December 10, 2015, but did not alert people who had purchased the products to the danger, the Foxes allege; the Foxes bought their hoverboard in November 2015, and the device caught fire in January 2016. Amazon declined to comment on the specifics of the case.

Amazon also does not make it easy for customers to report when they receive a product that shouldn’t be available on the site—whether because it’s banned, like the 18650, or because it’s counterfeit. Last year, Richard Bock bought Gillette-branded razors on Amazon, not stopping to question why they were so cheap. When they arrived and he opened the packaging, which looked like official Gillette packaging, he realized that the blades were uneven. He called Gillette customer service, which asked him to read a number from his package and then confirmed that they were counterfeit. But when he tried to post a review on Amazon to alert other customers, he received a message that the review could not be posted, because it did not adhere to Amazon’s guidelines. He had written a review naming the seller who he says sent him counterfeit blades, but Amazon allows reviews of only products, not sellers, to be posted on a product page.

Amazon invests substantial resources into ensuring the products sold on its site are authentic, a spokesperson told me, adding that the company ensures that more than 99 percent of the products that customers view on Amazon never receive a complaint about counterfeits. In 2017, it launched Brand Registry, which allows companies to flag suspected infringing content.

But it also warned, in its most recent annual report, that sales of counterfeits present a risk to its business, because it reimburses buyers in certain situations. If counterfeit or stolen goods are sold on its site, Amazon said, the company could face civil or criminal liability. This is the first time Amazon has listed the sales of counterfeits as a risk in SEC filings.

Some lawyers are pushing the courts to examine Amazon’s just-a-platform argument. Vincent Greene is representing Kyle Melone in his case against Amazon and LG, and told me that if a brick-and-mortar retailer such as Best Buy sold the battery that set his client’s leg on fire, it would be responsible for injuries related to the product. There’s no reason Amazon should not be similarly responsible, he said. The lawsuit argues that Amazon was aware of the probability that the battery Melone purchased would be dangerous, but that it did not warn him, and so “acted in conscious disregard to the safety” of his client. “This is where he went to purchase his battery. It’s no different than if he went to Best Buy and pulled something off the shelf,” Greene told me.

Rohwer, of Business for Social Responsibility, points out that the United Nations’ Guiding Principles on Business and Human Rights states that businesses have a responsibility to protect the human rights of their customers, even if they are not directly to blame for those human-rights violations. “There’s a real absence of due diligence if a company doesn’t know what it’s selling,” he told me.

Holding Amazon responsible for everything sold on its site would be extremely difficult, though. Sellers who participate in the Fulfillment by Amazon program ship their products to Amazon for them to be stored and then shipped out. But if multiple sellers are listing the same product, those products are stored in the same bin at Amazon, Kaziukenas said. That can mean defective, dangerous, and counterfeit products are being stored—and shipped—alongside legitimate ones, and that Amazon may have a hard time knowing which seller sold which.

“Sharing identical inventory is a unique process that allows Amazon to efficiently process, fulfill, and ship customer orders,” an Amazon spokesperson said in a statement. “The system is purposefully designed so that similar products are not placed next to or near each other, and items are tracked digitally allowing Amazon to determine provenance when needed. Selling partners are able to choose whether or not to share identical inventory.”

The current law requires Amazon at least to try to police its own site, Eric Goldman, a co-director of the High Tech Law Institute at Santa Clara University School of Law, told me. Amazon must apply a “rigorous” takedown procedure to products that it learns are counterfeit, violate trademarks, or are otherwise problematic. But if the company could be held liable for everything it sold, it would have to sell far fewer things. “E-commerce would look a lot different if the marketplaces are responsible for selling goods,” he said.

There is one way, though, that lawyers think they can hold Amazon accountable. That’s in cases in which Amazon itself, not a third party, is the seller. In 2017, Daimler AG sued Amazon for selling counterfeit versions of Daimler’s Mercedes-Benz wheel-cap centers—the products were listed as “shipped from and sold by Amazon.com.” (The case is pending in U.S. District Court in California.) An electronics company called Fuse Chicken is currently suing Amazon for mixing in counterfeit versions of its product with legitimate versions, so that consumers ordering the same product get very different versions of it. (That case is pending in U.S. District Court in Ohio.) The 18650 batteries I bought on Amazon were also “sold by Amazon.com Services, Inc.” —in other words, the company itself, not a third-party seller. Amazon declined to comment on these specific cases, but did direct The Atlantic to a handful of lawsuits in which it partnered with brands including Vera Bradley and TRX to take action against people allegedly selling knockoffs.

As the legal battles continue, consumers are still buying products that could be dangerous. Nicholas Jones told me he had tried to boycott Amazon after his battery fire—but he’s planning a wedding, and the site proved an extremely convenient place to buy the many sundry things he needs. But now he goes through a little mental dance when he buys products on Amazon. “I click ‘OK,’” he said, “and then think, I hope it doesn’t blow up.”