EFF report Unintended Consequences 12 Years under the DMCA

This document collects reported cases where the anti-circumvention provisions of the DMCA have been invoked not against pirates, but against consumers, scientists, and legitimate competitors.

In practice, the anti-circumvention provisions have been used to stifle a wide array of legitimate activities, rather than to stop copyright infringement.

Source:
http://www.eff.org/wp/unintended-consequences-under-dmca