At least in Finland there's a specific law about journalistic source protection (lähdesuoja) explicitly saying journalists have the right to not reveal sources.

In serious crime cases in some circumstances a court may order a journalist to reveal sources. But it's extremely rare and journalists don't comply even if ordered.

https://fi.wikipedia.org/wiki/L%C3%A4hdesuoja

Edit: the source protection has actually probably never been broken (due to a court order at least): https://yle.fi/a/3-8012415

Thanks for the info & link! After some searching, I found this rather interesting study on source protection in many (international) jurisdictions, and it calls out Finland, though other countries have interesting approaches as well: https://canadianmedialawyers.com/wp-content/uploads/2019/06/...