this is a first draft, please comment with suggestions.
Changing Terms
When the Founders first set the length of a copyright term, it was a period of 7 years from the date of the work's creation, with the chance to renew it for an additional 7 years at the end of the first term. The longest a work would be under copyright in this system was 14 years. In today's system, the shortest a copyright term will be is 70 years, which assumes that the creator of the work dies the day that the work is created. For anonymous works, the term is 95 years from the date of publication, or 120 from the date of creation, whichever is shorter.1
So on average, a copyright term today is about 95 years from the date that a work was created. This is more than the average human lifespan, with only an estimated 403,000 out of nearly 273,000,000 people in the US2 being over the age of 95. This is only .15% of the population. With numbers like these, it's highly unlikely that a person born today will live to see a work created today enter into the public domain. For those of us already alive, it's entirely possible that two generations may pass before a new work enters the public domain.
But is this the way things should be? It certainly doesn't seem to fit with the original intent of copyright in the US, which was "[t]o promote the progress of science and useful arts, by securing for limited times to authors and inventors the exclusive right to their respective writings and discoveries."3 This language, with a maximum initial copyright term of 14 years, seems proof that copyright was created to be a very limited protection that should entice people to create and release material.
I say "create" because copyright is, and always has been, an artificial creation. Physical property has always been a clear-cut thing, with people being assured of protection against theft or destruction of physical items they own. Intellectual property, however, is entirely different and should not be looked at the same way as tangible property. Once often cited difference between the two is that if a tangible item is stolen from someone, then they no longer have that item and are unable to use or enjoy it, while if an idea is "taken" then its creator still has the idea and their ability to use it isn't changed at all. That ideas do not diminish with distribution is the single greatest thing separating the two types of property. Among others is that ideas can be independently reached by two or more people or groups, through entirely different means.
This isn't to say that copyright (and intellectual property, in general) shouldn't have any legal protections, I fully agree with the intent of the Founders when they chose to protect IP to give an incentive to keep creating. The problem is the evolution that copyright has taken, with the form that it exists in today.
On of the largest changes to copyright law took place in 1976, when Congress completely changed copyright law. No longer were works required to display a copyright notice to be under the protection of copyright. Anonymous works were given different protections than works with a known author. Most importantly, the term of copyright law was changed dramatically. Prior to the 1976 act, the length of a copyright term was 28 years, with the option to renew for an additional 28 years, yielding a maximum term of 56 years. After the change in the 1976 act, works before 1978 were protected by an automatic 47 year renewal (if they hadn't yet renewed) at the end of their term and new works were protected for the life of their creator plus an additional 50 years.
These changes were mostly made to bring US copyright law into line with that of other nations, as decided by the Berne Convention. And in that regard, it did, and from that point on the terms of US copyright and that of European nations was much the same, up until the passage of the 1998 extension act, which was claimed to "harmonize" US copyright with the rest of the world, but in reality made our term longer than that of most other countries.
The length of a copyright term is not the only thing that has changed about copyright law since it's inception. The protections that copyright provides have changed significantly, mostly brought about by the 1998 Digital Millennium Copyright Act (DMCA). To most people involved with computers or digital media in any way, the DMCA is something of which they are very much aware.
Massive Changes - The DMCA
The DMCA was ostensibly passed to ensure copyright protection to works in digital format, since it is much easier to disseminate a digital work than a physical one, with no loss to the quality of the original. This in and of itself is not a bad thing to do; however, the DMCA takes this idea and gives copyright holders an unprecedented amount of control over the use of their created works.
One of the more disturbing sections of the DMCA prohibits distributing information that could be used to defeat digital copy protection. The act of copying itself is already covered, and on top of that, the DMCA makes it illegal for anyone to describe how to get around any protection on that work. This imposes prior restraint on security researchers who wish to make available a bulletin about some protection mechanism, for example.
Let's take a hypothetical example to illustrate the point. Suppose that a CD is distributed with a special player bundled, so that to listen to the music on a computer, you have to use this player, because the songs are encrypted. If you buy the CD, and look at the encryption, and you find it to be ROT13 (one of the simplest encryption algorithms in existence), then if you published that fact, you would be open to lawsuits under the DMCA for allowing others to circumvent that encryption.
At no other point in history has a copyright holder that the ability to dictate in what way a work may be used. Any such restrictions were always contractual, and never through copyright law. With the DMCA, however, the copyright holder can practically dictate the time, place, and circumstances under which a work may be used. Should someone attempt to defeat the access control (no matter how simplistic it may be), then they are liable to being sued for violating section 1201(a)(1) of the copyright code.
To put this into a slightly exaggerated context, let's show another hypothetical case. Suppose that a publisher releases a book that has a lock, preventing you from reading it, unless you use the key attached to a certain kind of chair. In that case, you are bound to that particular chair for reading the book, and if you picked the lock to read the book anywhere, or told anyone how to pick the lock, then you would have violated the DMCA. This example is a direct analog to a situation which already exists in the computer world.
Some CDs are now coming with a special data-only track that is only readable on computers. This means that a normal audio CD player should play the CD normally, but a computer cannot. This data track contains digital versions of the tracks on the CD in Microsoft's proprietary Windows Media format, which can only be played in Windows Media Player, only available on the Windows operating system. This means that the files cannot be played on a Mac or a machine with Linux, for example; and to convert the files to a open format would be a violation of the DMCA, since the proprietary encoding constitutes an access control mechanism.
Another thing the DMCA allows copyright holders to do is 'order' a hosting provider or ISP to shut down an account accused of infringing on their copyrights. This is done with absolutely no judicial review of any kind, and can be an automated process. This means that at no point does a human ever see what files (if any) are being illegally distributed though the site in question, and recently has generated quite a few false positives. The DMCA attempts to discourage broadly sending takedown notices, by providing penalties if notices are sent that are known to be false or misleading. This is very shallow, and doesn't cover the situation where the notices are automatically sent (since nothing was done 'knowingly'). It probably doesn't even cover the case of an actual person sending out notices to every website starting with the letter 'n', since that person wouldn't know that a site wasn't infringing.
The lack of any burden of proof on the part of the copyright holder means that they can request any site be taken down, without the need to explain why (beyond saying "they're infringing"). To prevent themselves from being open to liability, a hosting provider or ISP who receives such a request will likely take the site down ASAP, and then notify the site's owner that their site is down. The potential for abuse here is staggering, and it's quite possible that this section of the DMCA could be used to create some sort of censorship (by sending a takedown request alleging copyright infringement).
There is absolutely no reason why a copyright holder who suspects a site of copyright infringement shouldn't have to get an injunction from a judge to shut down that site. This introduces an (ideally) impartial third party who needs to assess the merits of the copyright holder's claim before allowing a site to be shutdown. If the site in question is found to be infringing on copyrights, then by the order of the judge, the site can be shut down and the owner sued under regular copyright law. Removing this aspect means that the copyright holder is judge, jury, and executioner, and there doesn't even need to be a human who knows when a notice is sent.
One of the claims supporting the DMCA was that digital works are different from traditional works, and should have additional protections since they can be shared or distributed much more easily. It may be true that it is easier to infringe copyright with a digital work than a traditional physical work, but not to the extent that a whole new set of ambiguous and revolutionary laws need to be passed to ensure that a work remains protected. It's not as though an infringement of copyright with a digital work isn't covered under traditional copyright law, because any traditional copyright law applies to all works, whether they're digital or not.
The aim of the DMCA seems to be preventing infringement from taking place in the first place, instead of waiting for an infringement to take place. This is the wrong attitude to take, and flies in the face of copyright since it's inception. You could make a photocopy of an entire book, but if you tried to print your own and sell them, you would be infringing on the copyright. Digital rights management (DRM) is the digital equivalent of the copier not letting you make copies of the work. The DMCA makes it illegal for you to make copies of it anyway.
In no other area of law is this the case; the idea is that the punishment for the offense discourages the commission of the crime. I can go around and talk about the best way to kill someone, and this itself is not illegal. I can purchase a knife, which could potentially be used to kill someone, and this itself is also not illegal. As soon as I use that knowledge and that knife to kill someone, I haven't done anything illegal. The same logic applies to nearly every law on the books, with the exception of copyright. If I talk about the best way to break the CSS encryption on a DVD, I've violated the DMCA. If I made the code for DeCSS available, so that a Linux user can play a CSS-encrypted movie, I've violated the DMCA. In neither case did I infringe on anyone's copyright, yet in both cases I've broken the law.
Another of the weak points of the DMCA is that it tries (on the surface) to allow easing of it's restrictions. The hearings and Library of Congress rulemakings on exemptions from §1201(a)(1)(A) are one way in which the DMCA appears to allow easy changes so that legitimate uses of works are allowed. Looking harder, though, we see that this just superficial, and that there is no easy way to prevent fair uses from being covered, or from legitimate uses from being stifled. Even with an exemption from §1201(a)(1)(A) (which covers circumventing an access control to a protected work), the prohibition on manufacture or distribution of tools facilitating this (§1201(a)(2)) still applies, and so to circumvent an access control, a person would have to develop a tool entirely from scratch, entirely on their own.
In Closing
Over the last 200+ years, copyright law has changed dramatically. Most of these changes, however, have come in the last 50 years, with the extensions of the 1976 Copyright Act and the 1998 Sunny Bono Copyright Term Extension Act, and the massive legal creations of the 1998 Digital Millennium Copyright Act. None of these changes seem to fit with the original intention of copyright as written by the founders, or even with those changes made to copyright law prior to 1976 (with the exception of the short extensions made in the 1960s and 1970s leading up to the 1976 act).
Copyright, like all laws, is and always will be evolving. But the evolution of copyright is not like that of any other law, because no other area of law can be exploited by entertainment companies to maximize their profits though legislation and the resulting lawsuits. It has not been an evolution of societal views (as was the case with slavery and segregation), nor one of technology. It has been one of corporate profit, even when the profits are virtually nonexistent.
References
1. http://www.copyright.gov/circs/circ1.html#hlc
2. http://www.census.gov/population/projections/nation/detail/d1999_00.pdf
3. http://www.law.cornell.edu/constitution/constitution.articlei.html#section8