Amazon has changed the rules around the sale of USB cables after a Google engineer spent months reviewing the cables available through the site, The Next Web reports.

Google engineer Benson Leung noticed that Amazon changed its rules to prohibit the sale of USB-C cables that don't comply with standards for the cables. Basically it's banning the sale of bad USB cables that don't work.

Leung has spent months reviewing USB-C cables on Amazon. He's bought and tested hundreds of devices to determine whether they meet the USB-C standard. He found that many cables didn't, which caused issues charging certain devices and transferring data.

Here's part of one of Leung's USB cable reviews:

Benson here again, reviewing legacy USB Type-C cable on Amazon. Today I am reviewing SAWAKE's "USB 3.1 Type C Male Data Charging Cable Woven Mesh Cable Strong Braided". I bought this cable to use various USB Type-A chargers with the Chromebook Pixel and to do data syncing with Pixel C, and I found that this cable does not work to charge the Chromebook Pixel, or sync data to Pixel C.

Upon closer inspection, this cable does NOT comply with the USB Type-C specification version 1.1. The documentation can be found at usb.org under developers/usbtypec.

Specifically, these cables do not charge the Chromebook Pixel 2015 because the cable leaves the CC lines floating, where the specification requires a Rp pullup to Vbus to identify the cable as a legacy cable. Both pixel devices use the CC pullup to detect when a host has been attached. Since this cable has no CC pullup, neither device correctly charges or hooks up the data lines.