Originally Posted by geekmaster
In the USA, it is covered by the "Fair Use" doctrine, but it only applies to non-commercial personal use, and you cannot transfer or distribute your copy to others.
An example is the photocopy machine in public libraries. Another is the long-time tradition of making audio tape copies of music from a radio broadcast. Another example is time-shifting TV broadcasts for later viewing.
Fair Use uses that as a factor, but it's far from a sure thing as I understand it.
Those other case have all been explicitly upheld in court but they have in common the fact that the source material was legal for you to use in the first place. I'm not sure if the reasoning applies to the firmware issue if you had no license to use the firmware in that way. Same as it's not fair use to rent a DVD and make a private copy (CSS circumvention aside). You may not get caught or sued, but that doesn't mean it's fair or legal.