Nice post from Sharing is Liberty:
You can have Internet and free sharing of information, or you can have Working Copyright. You CANNOT have both.
Free internet is completely incompatible with working copyright. It is impossible to have both at the same time. I first read about this concept via Stephan Kinsella a while back but it took me a long time before I understood what he meant. I understand it now so I will explain.
Copyright can only be justified if it is effective.
In other words you need to be able to enforce it. Copyright works only if it is able to prevent your customers from redistributing their purchases (in order to achieve monopoly). Once the monopoly is attained, the copyright holder becomes the SOLE distributor which means, Every copy equals a sale. This is the definingcharacteristic of copyright. If it can’t do this then it isn’t even copyright anymore.