Reinforcing Apple’s argument that an FBI request for the company to unlock an iPhone in the San Bernardino terror probe could unleash repeated demands for help in other cases, newly released documents show that the Silicon Valley giant has received at least a dozen similar requests in courts around the country since last fall.

In a letter filed last week in federal court in Brooklyn and unsealed Tuesday, Apple’s lawyers told a New York judge that the company has received FBI demands to unlock iPhones in California, Illinois, Massachusetts, Ohio and New York for devices ranging from iPhone 3s to an iPhone 6 Plus, which has heightened security and privacy features. One of those demands came in an unspecified criminal probe in the Bay Area federal courts in December, when Apple opposed efforts to unlock three iPhones, according to the letter.

“The existence of the other cases shows this isn’t simply about one iPhone,” Theodore Boutrous Jr., one of Apple’s lawyers, said Tuesday. “What’s to stop the next court from ordering the same thing to happen?”

The letter was filed with U.S. Magistrate Judge James Orenstein, who has been weighing Apple’s refusal to unlock an iPhone in a Brooklyn drug case since last October. In previous orders, Orenstein has expressed concern about the FBI’s request but has yet to rule.

In the meantime, the issue has exploded into the public eye with a federal magistrate judge’s order last week in Riverside requiring Apple to help unlock the iPhone 5C of one of the San Bernardino County shooters, Syed Rizwan Farook, who was killed after he and his wife gunned down 14 people in a terror attack.

Apple CEO Tim Cook has pledged to fight the order, over the objections of U.S. Justice Department lawyers and the FBI, which argue that Apple is unnecessarily impeding a crucial terror investigation for marketing and business reasons. Apple has until Friday to file its formal legal response to the government’s arguments.

But Apple has already indicated that consenting to the FBI demand would threaten the privacy rights of tens of millions of iPhone users, giving the government unfettered access to the security protections built in to the ubiquitous smartphone.

The letter released Tuesday is part of Apple’s argument in both New York and California that the FBI’s requests go well beyond seeking access to iPhones in particular investigations, saying that cracking the encryption would provide a “master” key to unlock security in an avalanche of court cases.

All of the government requests for Apple’s help in unlocking iPhones have been filed under the All Writs Act, an 18th-century catch-all law at the center of the legal battle that gives the government wide leeway to seek court orders forcing individuals or institutions to take some action. Apple opposes the FBI demands in the dozen cases cited in its letter.

In court papers, federal prosecutors have criticized Apple’s privacy arguments, saying the San Bernardino request is narrow and would not force Apple to relinquish technical secrets that protect the privacy rights of customers. Federal prosecutors in the Brooklyn case previously disclosed that Apple has in fact cooperated in other efforts to unlock iPhones.

The showdown has continued to divide opinions across the country. While many tech leaders from companies such as Facebook and Google have sided with Cook, Microsoft co-founder Bill Gates on Tuesday told the Financial Times in an interview that he believes Apple can provide the aid to the government in the San Bernardino case without providing a backdoor to encryption protections in iPhones.

Meanwhile, other law enforcement leaders have expressed concerns about Apple’s position.

Manhattan District Attorney Cyrus Vance said his office has 175 iPhones it can’t open because of encryption, adding he doesn’t believe it should be up to Apple whether or not it cooperates with law enforcement.

“This has become, ladies and gentlemen, the Wild West of technology,” he said at a news conference Tuesday. “Apple and Google are the sheriffs and there are no rules.”

Howard Mintz covers legal affairs. Contact him at 408-286-0236; follow him at Twitter.com/hmintz.