Dear Ancestry Insider,
I believe there are quite a few databases hosted on Ancestry.com for which Ancestry.com is not allowed to charge. And I believe this has something to do with the copyrights of each of the databases. Of course, Ancestry.com does NOT publicize that many of their databases can be searched without a paid membership. Nor do they make it easy to figure out how to search these databases. (Hint: on Ancestry.com, navigate to 'Help' and typing in "free databases".)
Please correct me if I'm wrong. It's my theory that these free databases are the databases available through the FHC Edition of Ancestry.com. I think the general public can access these databases from any internet connected computer FREE OF CHARGE on the Ancestry.com website; I don't think users have to be in a FHC to do so.
You are essentially correct that legalities require that Ancestry.com offer some databases without charge. To be precise, this is required by contracts, whether the database is copyrighted or not. (See “Can I Freely Copy Public Domain Documents” for a little insight into the difference.)
It was when they introduced New Search 2008 that they started hiding which databases were free. Thanks for the hint about clicking on help and searching for “Free databases.” The help article explains how to use the old card catalog to see a list for free databases. Be careful; not every database listed is free. Only those marked are free.
The number of free databases is not large. Of their nearly 30,000 databases, less than 400 are free.
Per your request, I have one correction. Oddly enough, databases that are free at Ancestry.com are not available in the FHC edition of Ancestry.com. Access the free databases at home; access the free FHC edition databases at a FHC.
Thanks for your insight,
-- The Insider