Why are terror incidents always used as an excuse to cut civil liberties?

Why are incidents like the recent Woolwich killing so hyped up once the link to terrorism is established?

The pattern runs, police or/and security services label the killing terror based. Panic ensues, the government announce in a very loud voice that the COBRA committee is sitting. The implication is always that the incident is not that of isolated maniacs but an international conspiracy of 9/11 type proportions. Muslims as a group are blamed wholesale for any such incident.

The resulting hysteria among the public results in attacks on innocent Muslims. The far right has a field day, playing an active role orchestrating such events.

Finally, the call comes for more powers for the police and security services to lock up and intercept anyone they don’t like the look of.

How different the response is here to say Norway where following the atrocities committed by far right fanatic Anders Breivik, the Prime minister Jens Stoltenberg called for a response that brought "more democracy and more openness." How mature compared to the hysterical rush here to trample on ever more liberties - exactly what the terrorist wanted in the first place ofcourse.