Adam Serwer explains:

Russia offers an experiment in a country giving itself over fully to the most heavy-handed of responses to terrorism. Putin was given the freedom to achieve security by any means–and Russians have ended up with a state that is less secure and less free. There are strategic reasons for adhering to the rule of law, beyond actually preserving the kind of society that terrorists seek to destroy. Even when liberals make that case though, as Obama did during the 2008 election, we've fallen short at actually following through on those ideals. The U.S. is not Russia, but in Russia's example we might learn a few things about the limits of unrestrained force alone in defeating terrorism.