As I'm sure you've heard by now, there is a lot of unrest in Egypt right now, including some major demonstrations and protests against the current Egyption government. In an effort to quell the protestors and assert their control, the Egyptian Government has effectively shut down the Internet in that country. Here is a nice visual demonstration of that from the Arbor Networks (via Reason):

We should remember this as Congress begins to reconsider the Protecting Cyberspace as a National Asset Act of 2010, otherwise known as the "Internet Kill Switch Bill". The authors promise (as they always do), that it won't be abused. And yet the language in the bill is generally very vague, and leaves much of the interpretation of the act to a yet to be created office in the executive branch. And while the bill mentions that many private companies will be able to "volutarily" submit to certain parts of the act, it's clear that voluntary action by ISP's are rarely voluntary. Anyone who remembers their submission to warrantless searches during the Bush Administration will tell you that.

The authors suggest that it's necessary to "require infrastructure connected to 'the system that controls the floodgates to the Hoover dam' to cut its connection to the net if the government detected an imminent cyber attack", but what they don't say is how the government would know when such an attack were imminent, and more importantly, why a network wouldn't voluntarily disconnect if it were made aware of said attack.

The fact is, there is no need to create a mechanism to force any company or network to do what they are asking, because any company would volutarily disconnect in any of the scenarios where they say such force would be used. So the only reason to create a mechanism to forcefully disconnect a network is when nobody would do so voluntarily... and that is a scary thought.