It is the worst kind of myth. It is wasteful, achieves nothing, gives a false sense of protection and can leave good people more vulnerable than if they had done nothing at all. There is simply no way that poor man's copyright is a valid strategy for protecting one's work.
Yet, even today, it is widely preached, especially in comments to blog posts
What is Poor Man's Copyright?
The idea is simple. You create a work, be it a written piece, a photograph, a drawing or a CD, and decide that you can't afford or don't want to pay the U.S. Copyright Office fees to register your work formally. So, rather than send your work to Uncle Sam, you put it in a nice, shiny envelope and mail it to yourself. Upon its return it has both your name and a nice date stamp, proof positive that the work belonged to you on that date and was created before that.
You spend less than a dollar and get proof positive of both the date the work was created and who the owner is. All you have to do is keep the envelope in a safe place and never open it up.
The theory from there goes as follows. In the event of a later copyright dispute, you take this sealed envelope with you to court and open it up in front of the jurors, judge and gallery proving that the work is yours. One hopes that there is no way they can lose a copyright case with such solid evidence on their side.
Unfortunately though, both the case and evidence are weaker than thought. In fact, both might turn out to be worth nothing at all.
Unicorns, Leprechauns and Poor Man's Copyright
The problems start early for PMC. Simply placing a work into an envelope and mailing it to yourself does not prove ownership. You sign no forms, make no statements and offer no proof of creation. People mail things that they do not hold the copyright to all of the time and the courts know that.
Second, envelopes can be steamed open and postmarks can be smudged, altered or unreadable. While you can mitigate those by sending the document special delivery, which offers better sealing envelopes and clearer postmarks, it is more expensive and likely can't be done from home.
Then, in the courtroom, things don't get any better. First off, the court room will not be a federal one, but a state one. Since you didn't register your work, you can not sue in federal court and, thus, will only be eligible to receive either the amount the infringement made or the amount you lost, whichever is greater. Sadly, in many, if not most, copyright matters that amount is equal to exactly zero.
However, the worst news is that most copyright cases don't center around issues of authorship. They center around matters of fair use, contract disputes and unauthorized duplication. While plagiarism is rampant, as this site shows, it is generally simple to find out who the original author was and it is unlikely that PMC would be needed to prove that. Furthermore, especially in the Internet age, if a dispute of authorship should arise, the delay in receiving back the envelope would likely make PMC harmful to the case since such infringement happen with a matter of minutes, not days.
In short, your proof would likely arrive and be dated AFTER the infringement took place, providing no aid to your case and, possibly, helping the plagiarist.
In the end, all PMC does is give you weak evidence to take to a smaller courtroom and present a potentially damaged case centering around unrelated issues. Most copyright holders would be better off doing nothing at all than trying to take advantage of PMC.
This is probably why, to date, no case in the history of the U.S. has been aided by PMC and, most likely, none ever will.
If you want to protect your works, there is simply no substitute for the U.S. Copyright Office. Though copyright takes effect once the work has been fixated, registering your work there not only provides you with formal documentation to prove the submission took place, but also with the right to sue in federal court and claim punitive damages for infringement of your work.
The Copyright Office, however, can be slow and carry with it many of the same problems in terms of delay that PMC has with it. That, however, can be mitigated by using Numly to provide instant timestamping and third-party non-repudiation of your work. Even though Numly may not be formal or official, it is many times better than PMC and, in most cases, is free. It's an ideal tool for bloggers while they are waiting for their formal submissions to go through.
Also, don't forget that services such as the Web Archive and Google cache automatically save copies of a Web page, providing some ability to prove dates and times. These archives may or may not work well in a court of law, but are more than adequate in most copyright disputes.
In the end, PMC has no place in the arsenal of copyright holders, especially if they are American. Other countries, depending on the nuances of their copyright statutes, may have some use for it. However, even then, there are much better, cheaper and easier methods available. I seriously doubt that PMC is a good option for anyone, let alone the best.
It is time to crush this myth once and for all. If we, as copyright holders, are going to get serious about protecting our works, we can't let ourselves cave into convenient myths and misguided ideas. PMC is useless and, no matter how much want it to be a practical solution, it never will be.
Fortunately, very good and reasonable alternatives do exist. All we have to do is stop hanging on to the old ways and be willing to try new things.