Ontario Law Stamps - Looking For Some Historical Background

Hello friends!

New to the forums, but a longtime collector here getting reacquainted with philately... that said, I'm looking for some historical background on Ontario Law Stamps. Came across one in my collection and it had a hole punched in it instead of a postmark (eek!).

If anyone can tell me some more on how these stamps were used, how long they were in circulation for etc, and how I might be able to grade mine (is there a Scotts entry for these stamps?) I'd greatly appreciate it.

Regards,
Eros

This link might be of help: https://www.canadarevenuestamps.com . E. S. J. van Dam has a nice catalogue available and also offers revenues for sale. Might be a starting point to getting information.