'In the matter of' is a translation of the Latin re. (This is relevant because for many years Latin was the main legal language - which is why legal terminology is scattered with Latin phrases like prima facie and habeas corpus.)
A matter of concern or discussion or activity of some kind for lawyers doesn't always lead to a court case. The legal matters reported in newspapers, however, often are court cases. So, prima facie (on the face of it/at first glance), I'd expect lawyers to use both words and journalists to use 'case' (which has the added benefit, for journalists, of being shorter - more appropriate for use in headlines and in text when the column is narrow).
- For Teachers