I was asked in a comment why the CRKN announcement about the new collaboration with Canadiana.org mentioned Creative Commons licensing.
What is in the public domain stays in the public domain. What Copyright restricts, this project will be releasing under a Creative Commons license. It is copyright law which defines the line between the public domain and what must be licensed.
I am a system administrator at Canadiana, and not someone involved in policy relating to licensing of the parts of this project that will be covered by Canadiana copyright. When it is a Canadiana decision, it is our Board of Directors made up of librarians and archivists, and our executive director, who ultimately are responsible for such policies.
As someone who has spent more that a decade dedicated to Copyright related policy discussions (see Digital Copyright Canada), and been involved in the Free Software movement since the early 1990's, I have my own opinions -- but they are my own and not those of Canadiana.
A work that is in the public domain in Canada is something which has fallen out of Copyright. For most things that is life of the author plus 50 years. We have researchers at Canadiana that work on determining the author of works we wish to scan and a database of the deaths of authors to help with the public domain determination.
Copyright term extension has unfortunately been threatened by the federal government many times. This sometimes comes in the form of treaty negotiations such as the Trans-Pacific Partnership (TPP) and the Canada-Europe Free Trade Agreement (CETA), with our trade representatives never adequately pushing back on calls for term extension. In some countries term extension has even re-regulated works that were already in the public domain. This is a risk of any project like ours given we rely on the public domain to be allowed to make the scans in the first place.
In order to scan for this project Canadiana or LAC essentially take photographs of the books, papers, and other articles being preserved and made accessible. Then the photograph is digitized (sometimes from film previously taken, and sometimes more directly as part of the book/paper scanning process).
It is unfortunately a matter of debate whether a photograph of something which is not restricted by copyright has its own separate copyright held by the photographer. This ties into the debate about sweat of the brow vs originality. While there are some professional photographers and their unions who believe that all photographs should be restricted by copyright, regardless of subject matter or originality, I believe most Canadians (including many lawyers reading some of the relevant caselaw, which helps) would disagree.
To avoid being dragged into this heated debate, and to protect against future changes to copyright law, a license provides clarity even for those who wish/believe the photograph has its own new copyright.
If the decision was mine (note: it's not -- talk to your Librarian :-) any license on the photographs and resulting scans would be CC0 which is a method to try to put a copyrighted work as closely to the public domain as domestic law allows. This avoids the question of whether a public domain dedication is possible in Canada by providing a back-up license.
Scanning is only part of the process, and not the part that takes the most resources. Researching metatata about the images so that there is something to search on creates a new database. All this metadata is considered new works under Copyright, and thus a license is required.
There may in the future be crowdsourcing of metadata, and legal clarity will be required there as well. I'm personally a fan of joint-copyright assignments or copyright waivers (CC0 style) for projects like this to allow the non-profit (in our case charity) project to enhance licensing over time.
There are plans, if funding comes together, to transcribe some of the handwritten papers. More than the photographs there is a presumption that the transcriptions would have their own copyright, so licensing is required.
Hope this helps... I wish copyright weren't expanding all the time, but as it does there is an increased need for licensing where previously copyright wasn't relevant. The scope and term of copyright is expanding at the same time as exceptions (such as fair dealings) is largely being diminished globally. There were some minor fair dealings gains in Bill C-11, but there were far more losses. Canadian copyright law will also be manipulated by Bill C-56, the bill allegedly dealing with counterfeit materials where most of the controversy is in the unrelated copyright aspects.
Note: Being part of the Free Software movement I prefer the subset of Creative Commons licenses which are similar to those we use. I have never liked the vagueness of the so-called "Non Commercial" (NC) clauses, and thus them and have a preference for CC0, CC-BY and CC-SA. With the definition I use for "open access" this is what is required, and don't consider works licensed with a ND (no-derivatives) or NC to be "open access". But, as with many things, different people use different definitions.