"Copyright & the news reprint" - Judy Russell discusses copyright and public domain and how that affects using digitized newspaper images of whole newspaper pages as well as copies of hard copy newspapers
"Copyright & the newspaper article" - here's more detail about copyright laws and newspaper articles in particular
You can also search The Legal Genealogist's blog for copyright law as it pertains to obituaries, another newspaper-related topic.
These lists are extremely helpful in determining whether your ancestral locations have newspapers digitized at Google News Archive. Jose did inform me that there were some general, rather than specific, locations listed and I did find a couple minor errors--Yukon Territory (part of Canada) being listed under Alaska, for instance--but as a whole, these are amazing resources and a great deal of work and time were expended creating them. I ought to know, as I've only started adding the titles beginning with the letter "B" to my Online Historical Newspaper site!
I trust these two blogs will be of great assistance in your newspaper research!