Michael Perelman wrote:
> intellectual property is an abomination in its present 
> form.  Libertarians used to oppose it as monopoly.  What 
> happened to contemporary Libertarians? 


My sense is that modern libertarians oppose patents but 
support copyright.  I am thinking of Rothbard
(e.g., <URL:http://www.ccsindia.org/lacs/7patents_copyrights.pdf>)
but in the software arena I suppose one might also think of
the higher profile Richard Stallman.

That does not answer the crucial questions: what is covered 
by copyright, and how long does copyright last?  I assume
Rothbard would construe copyright narrowly and then make it
permanent, but I cannot cite evidence for that.

In the US, both copyright and patents have a clear 
constitutional justification: Congress has the right to 
create copy rights and patent rights to the extent that this 
promotes "progress"
<URL:http://www.usconstitution.net/const.html#A1Sec8>

It may seem obvious to an economist that Congress has 
exceeded this constitutional mandate in the copyright area, 
but recall that Lessig lost his argument in front of the 
SCOTUS by a brutal 7-2.

One thing that keeps this all a mess is that in 1790 
Congress passed a copyright law which applied retroactively.
This has been interpreted to say that the founders did not 
believe copyright extensions to violate the "limited times" 
requirement. From a modern economist's perspective, there is 
retroactive application raises problems for the progress 
justification as well.  

Cheers,
Alan Isaac