Test print from an HP Colour LaserJet 3700, showing the yellow dots
The Electronic Frontier Foundation (EFF) found OKI and Samsung were the only OEMs whose printers did not print yellow dots on each page to register the device’s serial number and add a timestamp.
The EFF said that the US government asked printer companies to utilise the codes as a means of tracing counterfeiters, Techly reported, while noting “there are no laws to stop the Secret Service from using printer codes to secretly trace the origin of non-currency documents”.
A list of almost 200 printers from 20 printer manufacturers, including a number of Canon imageRUNNER and HP LaserJet devices, was compiled by EFF, with only OKI and Samsung printers not showing the microscopic dots, which appear under a blue light.
A few dozen printers from other manufacturers did not have the dots, although EFF said they may still be present, as “other forensic marking techniques have been invented”. The group further concluded, based on documents obtained through a FOI inquiry, that all major OEMs had made a deal with the US government to include the information.
The Techly piece concluded that “all of this is a pretty good explanation for why your printer won’t print in black when you have black ink, but no colour ink”.