body: In [this answer](https://opensource.stackexchange.com/a/1673) on another SE, it is suggested that the anonymous authors of a piece of software might use a "[poor man's copyright](https://en.wikipedia.org/wiki/Poor_man%27s_copyright)" technique to establish that they possessed the work before it was published, in case they ever want to assert their copyright. This could consist of an unopened letter with a date stamp, a notarized copy, or some other scheme involving a third party. According to the wikipedia entry there is no specific provision for this in US copyright law.
  
  
  Is there any legal reason to use a "poor man's copyright"? Have these techniques been used successfully in court, or are they mostly useless? And if one wanted to use such a technique, what is the best way to go about it?
  
  
  I am looking for an answer for US law, but would appreciate other countries' perspectives too.
  
  
  
title: How does "poor man's copyright" work?