IANAL, but:

I don't know of any countries that do not recognise public domain as a concept, but there are many countries (including the USA) whose copyright laws have no provision for an author 'giving up' their copyright. Just saying "I release this into the public domain" does not necessarily do that, any more than walking away from a house you own means you no longer own it. That means that if somebody says "I release this into the public domain", there's no reason why they couldn't change their mind and sue you for infringing their copyright later.

For more information, see this FAQ on public domain: http://linuxmafia.com/faq/Licensing_and_Law/public-domain.ht...

Also note that Creative Commons has a special "Creative Commons Zero" license designed to provide the same results as "I release this into the public domain" in all jurisdictions, and it takes at least a page of legalese to do so: http://creativecommons.org/choose/zero/

TL;DR: saying "I release this into the public domain" probably doesn't do anything; just slap a BSD, MIT or ISC license on the work instead.

I think it's seen more as a problem for a) software with multiple contributors, and b) corporations that want to use open-source software. When there's no legally-recognized guarantee of rights to users of the software, you have to implicitly trust that the original creator will not change their mind and sue you later. In cases with multiple contributors, it adds that many more unknown entities with the ability to litigate. By releasing the software under a permissive license such as MIT or BSD, or even CC0, the legal wording is there to help guarantee your rights to use the software in the face of lawsuits.

"Ah sure, us using this software is technically illegal, but sure, the original author isn't going to come after us" is usually not a good line to write on your corporate "do we have enough licences audit"

The problem isn't that your might get sued, it's that you can't convince $POINTY_HAIRED_BOSS that you won't get sued.

YMMV, I guess, depending upon where you work/have worked but despite working in commercial software, I've had a bigger problem convincing past bosses that using pirated software to do our jobs is a problem than I have had with bosses who were overly concerned about copyright law to the point where it would be an issue in my hypothetical case.

I still think the original objection is more retold fairy tale than truth, but if anyone wants to prove me wrong they can point me to a country where public domain isn't recognized, but random user-written OSS licenses are and the country has any sort of culture of respecting copyright in the first place.

There is almost no country in the world where a work by an author that is alive or has died less than seventy years ago can be in the public domain. So releasing code as "public domain" more or less limits the release to the US.

> Nopublicdomainistan

Anyone said Germany? The concept of the "Urheberrecht" which many people falsly translate to copyright (it's more of a creator-right) is that you can not relinquish it in Germany. It's kinda like your mother can not "un-mother" herself from you ;)

That's why there's no real Public Domain in its purest form possible in Germany.

> clearly the author is never going to come after them. so what is the actual real world problem they face in this situation

The real problem is: A lack of legal certainty. You can not use PD in any bigger project if it is _possible_ that the original author might come after you.