Given the long title you could think that this is going to be a blog about a ridiculous edge case. It isn't, honestly! It is a blog about an edge case, but not ridiculous and not as far fetched as you think. Let's say that you have a class logging on DEBUG and TRACE. The debug messages contain (frequent) checks, but lack the full information needed to analyze the problem. This information (say a full xml message) is logged on TRACE level. Now your friendly system administrator decides that he needs this trace logging to go into a different file from the debug logging. He has good arguments and you don't want to pick a fight. Logback provides a lot of configuration options that you can do lots of neat things with. But it can't fill this requirement. Really? Well, there is a hack.