How Much Of A Music Score Can I Copy?
The use of music scores would fall under Dalhousie's Fair Dealing guidelines. As such, a music score is generally thought of as a single, individual work. The guidelines state that you may copy up to 10% of this type of music score that is published on its own.
If the score appears as part of a collection of scores containing other works, then the guidelines permit the copying of the entire score.
Music Scores and the Public Domain
Copyright protection in Canada lasts for the life of the author/creator and for the fifty years following the death of the creator of a work. At the end of that fiftieth year the work is considered to have entered the public domain and may be used without permission or payment to a copyright owner.
For those works that contain both composition and lyrics, they do not enter the public domain until the end of the fiftieth year following the death of all contributors.
There are a number of resources online that attempt to collect public domain music scores. Two such websites are Online Music Scores from Acadia University and the International Music Score Library Project (IMSLP).