(My favourite example is that America hasn't had a constitutionally-authorized war since World War II. https://en.wikipedia.org/wiki/Declaration_of_war_by_the_Unit...)
If it does, then SOPA would be subject to those limitations as much as any printing press law would (the example to which I was responding).
If it doesn't, then why does SOPA matter at all? The government could just shut down websites left and right tomorrow regardless of what the law says.
It's not uncommon for a law to be passed that is unconstitutional.
For example, the government might get away with indefinitely detaining a few people without trial; but they might still forbear to arbitrarily detain more than a few percent of the populace for fear of popular revolt.
It took nearly a century for the 14th Amendment to achieve the full force of law everywhere in the US.
We should not be the least bit blase about allowing unconstitutional laws to be passed, as though they would be null and void upon passing.
Why should anyone support that regardless of what sort of pretext is used to justify such an abuse of power? Should we round up all single adult males over the age of 40 out of a fear of pedophilia in order to "protect the children"?