Amazon’s $13.7 billion purchase of Whole Foods, announced Friday, will greatly accelerate what had been careful steps by the e-commerce giant into the world of brick-and-mortar retail.
But a patent dated May 30 details a possible plan for stopping customers from doing in its own stores what Amazon itself has been helping them do everywhere else for years: find better prices for the same products online.
The patent, which has been written about in Bezos' own Washington Post, details a method for blocking, redirecting, or otherwise controlling customers' attempts to comparison shop on their smartphones when using a store’s Wi-Fi network. The system would identify when a customer is trying to access a competitor’s website and take action. According to the patent description, it could block the action outright, redirect it to the retailer's own website, or distract the customer with a coupon or a salesperson's attention.
Get Data Sheet, Fortune’s technology newsletter.
The patent, titled “Physical Store Online Shopping Control,” has one obvious shortcoming: It can't do much to stop people from comparison shopping using their device's cellular network.
Nonetheless it is remarkable, though not exactly surprising, that Amazon patented the idea and not any one of the various retailers it has steadily ground down over the last two decades. With physical retailers unable or unwilling to match online prices, mobile window shopping, also known as "showrooming," has been partly blamed for the decline of retail institutions from Macy’s to Sears to Kmart.
As the Post points out, the fact that Amazon has the patent doesn’t mean it will use it. In truth, implementing such a system would likely be a public relations catastrophe.
But there's another interesting detail that highlights just how brilliant, and perhaps Machiavellian, Amazon can be. The patent was originally filed in May 2012. According to Google Trends, that’s nearly a year before online search interest in the term "showrooming" peaked.
In other words, Amazon was relatively early in addressing how mobile devices would impact physical retail. At a time when brick-and-mortar stores were barely a twinkle in Bezos' eye, Amazon filed a patent that would have put the company in a good legal position to stymie retailers' attempts to create a system that would keep customers offline.