For years, Uber used a secretive software tool known internally as “Greyball” to identify and steer its drivers clear of potential threats – including law enforcement officers hoping to catch Uber operating in their cities illegally. UPDATE: March 9 – Uber chief security officer Joe Sullivan announced late Wednesday that the company is reviewing its use of “greyballing” technology and “expressly prohibiting its use to target action by local regulators going forward.” Earlier: According to The New York Times, which first reported the story, the company deployed the software in cities that deemed the ride-hailing service illegal or otherwise tried to slow the company’s rapid expansion. The Times reports that Uber’s software clues into a number of signs from prospective riders to determine whether they might pose a threat to the company or its drivers, notably in the form of enforcement officers trying to catch Uber operating illegally. This includes the rider’s behavior using the app itself, such as the phone type, and patterns in the frequency of its use. Another clear tell: interacting with the app in close proximity to police stations and other government buildings. In 2014, for instance, officials in Portland, Oregon, sued Uber for operating in the city illegally, and promised to hit every driver caught working for the service with a fine of up to $3,750. The threat accomplished little, as Uber continued operating anyway. Portland officers pushed forward with sting operations in an attempt to catch the unlicensed operators, yet were stymied as drivers repeatedly canceled their rides, as this 2014 video by The Oregonian demonstrates: “There were two drivers that were available at one point in time, and they both canceled on me,” Portland Code Enforcement Officer Erich England comments in the video, giving a perplexed shrug. “Now there are no drivers available.” Portland Commissioner Dan Saltzman acknowledged the city’s relationship with Uber was “pretty tumultuous” in 2014, but he told The Huffington Post that doesn’t excuse the company’s behavior. “I’m appalled that Uber would direct its employees to work on developing software to deliberately thwart the efforts of Portland, and no doubt other cities,” Saltzman told HuffPost. He characterized the city’s regulatory efforts as dedicated to “the safety and wellbeing of our citizens and our tourists.” Portland and Uber smoothed over their relationship in 2015, but Saltzman said the city would consider levying fines or banning the company (again), should it run afoul of regulations. Uber maintains its software is completely legal, adding that it is used more often to keep its drivers safe than to circumvent sting operations. “This program denies ride requests to fraudulent users who are violating our terms of service,” an Uber spokesperson told HuffPost in a statement, “whether that’s people aiming to physically harm drivers, competitors looking to disrupt our operations, or opponents who collude with officials on secret ‘stings’ meant to entrap drivers.” That logic seemed pretty sound to Robert Weisberg, a Stanford Law professor and the co-director of the Stanford Criminal Justice Center, though he said he’d need to know the particulars of how it operates to be certain. “I’m not sure there’s anything illegal about it,” Weisberg told HuffPost. He noted prosecutors might have a case for obstruction of justice, but that “usually requires direct interference with the express purpose of preventing police from doing a very specific thing at a very specific time.” “If you or I were degenerates and up to no good – or at least thinking about no good – I could say, ‘Hey I just saw four cops on this corner, go the other direction’ or something like that,” Weisberg added. “This is just a huge technological enhancement of that capacity.” With a chuckle, he noted, “There’s great irony here in terms of police surveillance,” given that police departments continually push for an increased ability to track and collect data on private citizens, yet apparently object when the tables are turned. Legal or no, the bombshell revelation certainly won’t quiet criticism that Uber doesn’t take “no” for an answer and will bend any rule to get what it wants. That ideology seems to have manifested itself internally at the company, which finds itself embroiled in allegations of rampant sexism (and numerous high-level resignations potentially linked to the allegations). Other controversies rocking Uber at the moment include: a lawsuit over claims that Uber stole technology from a Google-founded competitor; fallout surrounding a video of CEO Travis Kalanick angrily telling off an Uber driver; and a #DeleteUber protest that wiped 200,000 users until Kalanick was pressured to resign from President Donald Trump’s economic advisory council.