I agree with Nils that this kind of censorship system can be designed at the 
protocol level to be resistant to abuse, or to be easier to abuse. For 
content which it is illegal to access, there is an argument to opaquely block 
it from users. For content where it is primarily the user at risk, however, 
specifying a protocol which exposes the reason for the blocking, and perhaps 
which provides a mechanism for choosing to get around the block, seems less 
of a problem. However, we must also consider how ordinary users will see the 
results, and work on HTTPS certificate problems could provide a good guide 
here on bad practice to avoid. We've trained people to ignore warning labels 
on web sites by producing so many false positives that many people will 
switch off the alert because they don't understand the information or the 
risk levels. So, providing the information at a deep technical level 
accessible to those with sufficient knowledge to know when to ignore it would 
seem the right approach, on an initial shallow analysis.

Such blocking is, of course, also linked to issue of net neutrality 
regulation.

-- 
Dr Andrew A Adams                      [log in to unmask]
Deputy Director of the Centre for Business Information Ethics
Meiji University, Tokyo, Japan       http://www.a-cubed.info/