Something that is expected, as in It was a matter of course that police officers received special training. It is also put as as a matter of course, meaning “as part of a standard procedure,” as in The employer checked John's references as a matter of course. First recorded only in 1809, this idiom uses course in the sense of “the natural or logical order of events.”
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.