Updated, from an article originally posted in November, 2013, because it’s still not legal.
I ripped a CD this morning; I violated copyright laws. In the UK, where I live, it is illegal to rip a CD. No one gets prosecuted, but the law is still on the books.
There is actually no law that expressly permits this in the US either, but case law and jurisprudence have allowed this act.
Copyright law is complex, in particular those parts of the body of copyright law that allow such things as time-shifting (recording something for later playback), and the ability to copy content to different devices or formats. Fair use allows much of this, but the laws are still strongly on the side of the content distributors, who would love it if we all bought multiple versions of content we want to use on different devices.
It’s clearly illegal to crack the content protection on DVDs and Blu-Ray discs, as well as certain other formats.
Keep this in mind the next time the movie or music industry go on a crusade. They try very hard to limit your choice of what you do with content you own.