The US Court of Appeals has thrown out a case stemming from the 2013 decision by the FAA to allow e-readers, smartphones and tablets to be used during all phases of flight. The Flight Attendants Union has been fighting this saying that people are glued to their devices and not paying attention to safety demonstrations.
The Washington Appeals Court ruled that the FAA has the authority to change its rules, including those for electronics on planes, when it wants to.
Airlines in the US, Canada and Europe have been allowing the use of electronics for a number of years now. It now looks like for the foreseeable future that reading e-books on your Kindle or listening to audiobooks is safe.