I have to say that I'm not a lawyer, but have dealt with copyright issues for a number of years, so am fairly knowledgeable. For the final word, you have to go to the lawyers.
Anyway, music copyright in Canada is quite different from the U.S., and many other countries in fact.
First of all, copyright is important for many reasons. If you use a work under copyright, most of the time you would have to pay licensing fees to the appropriate regulatory bodies. Works that have fallen out of copyright, that is, they are in the public domain, can be freely used for any purpose (and, in fact, you can do anything you want with them). They are under no protection.
Now, it also has to be recognized that there are multiple rights contained within a single musical work. We're only going to deal with the most common and important two - the composition, or music, and the performance. It's those two things that determine the overall copyright status.
We also have to define the term published. A musical composition is considered published when the sheet music is released for sale to the public. A performance is published, at least with the types of music that we'll be dealing with (prior to the 1960s) when a record or tape is manufactured and released for sale to the public.
All music in Canada is considered to have copyright protection the moment it is created, regardless of whether it is published.
Now, up until 2015, the copyright protection for a musical work was 50 years after the calendar year in which it was published. More for unpublished works, but they're not being considered here. In 2015, the laws were changed to extend that to 70 years. However, those performances that had fallen into the public domain (i.e., all performances prior to 1965) remained there.
Now on to musical compositions (music and lyrics). Up to 2022, the copyright protection for music was the lifetime of all composers plus 50 years. That was changed in 2022 to be life plus 70 years. Again, those music compositions (including lyrics) that had fallen into the public domain 2021 or earlier remained there.
So what does that mean for a radio station playing public domain music (in Canada). How do you determine if a work is in the public domain?
Well, first (the order doesn't really matter, although this is the simplest first step), look at when the recording was published. If that date is 1964 or earlier, the performance is in the public domain today. That's a lot of performances.
But wait, there's another consideration. The music itself. To ascertain if published music is in the public domain, you have to first determine all the creators. Then, for each one, find out when or if they passed away. Kind of morbid, but it has to be done. If all of them passed away in 1971 or earlier, then the music is in the public domain today.
If both of these conditions are satisfied, then the work is likely in the public domain in Canada today.
Why only likely? Because the copyright status of a work can be changed by a court decision. These are few and far between, and mostly occur with relatively recent music, not what Artisan Radio plays. And it usually involves adding a creator to an already copyrighted work.
There are also other rights, such as moral rights (protecting the creators reputation and integrity of the work), mechanical or reproduction rights (reproducing the work), etc. that last as long as the work remains within copyright. But once a work is in the public domain, they no longer are valid.
These rules can lead to some interesting situations with the copyright status of a musical work. For example, Jimi Hendrix wrote a number of songs. including Purple Haze. The first publication of that performance was in 1967, and he passed away in 1970.
At the time of the performance publication, copyright protection would extend until the end of calendar year 2017. But since the rules were changed in 2015, and the work was still under copyright at that time, copyright was extended by an additional 20 years to end 2037.
However, the music itself would have been protected by life plus 50 years, until the end of 2020. When the rules were changed in 2022, the music had fallen into the public domain, and would remain there.
So we have the unlikely situation where any artist today can perform the music of Purple Haze freely, but the original performance by Hendrix is still protected by copyright.
If you think that is confusing, you should look at the copyright rules in the U.S. But since this is a Canadian Blog, we won't do that here.