Z:gnu-www-ja-google-engineering-talk--3e09d2-One of them is the DMCA, which/en

One of them is the DMCA, which has been used to prohibit the free software to play a DVD. If you buy a DVD, it's lawful for you to view it in your computer, but the free software that would enable you to do this on your GNU/Linux system has been censored in the US. Now, this affects a fairly narrow range of software: software to view encrypted media. But many users may want to do that, and if they can't do that with free software, they may take that as a reason to use non-free software, if they don't value their freedom.