The Internet introduces many challenges for governments, particularly the part thereof involved in policy-making.
Governments from countries such as China, Saudi Arabia, Singapore, Australia (yes you heard right) have resorted to simply banning websites they consider harmful to the public at large.
In most western countries, control of the Internet has been informal, if existent at all.
I for one think that this informal control (such as peer-pressure for instance, or even market forces) has been reasonably successful given the alternatives.
Blocking the access to so-called illegal websites is too risky a measure to be taken by any democratic country, with regards to the obvious consequences it can have and precedent it can set.
That's when a government does not blatantly blocks website due to political resons alone, as is the case win China, Saudi Arabia and other non-democracies around the globe.