JCL loggers don't have configuration - JCL, like SLF4J, is a facade, not an implementation.
Ah, I wasn't aware of that. (This does not change the matter, but I might be able to get better at avoiding misleading terminology.) I'm using logback as the logging backend, that's why I'm using logback and SLF4J interchangeably when it comes to configuration. Of course that assumption doesn't transfer to all other projects, and certainly not to SLF4J in general, so that's another source of confusion. Sorry for that. With "SLF4J configuration", I mean whatever configuration the logging backend uses. It is even "the SLF4J configuration" in a broader sense: you can query SLF4J about its properties. It's just a subset of these properties, namely the logging level of each individual logger, and you need to know the logger's name in advance, but it's a queryable configuration all right. Now that terminology is hopefully cleared up a bit, here's what I want to achieve: Right now, the JUL bridge docs tell me to install a Level.ALL JUL root handler and let SLF4J sort out which messages are actually needed. The docs rightfully warn that that can have a performance impact. Very rightfully so actually. So for each logger that's configured for SLF4J, I want to create a JUL logger with the same logging level as its SLF4J counterpart. This should drastically cut down on the number of log messages created and thrown away. I hope this is getting a bit clearer now :) Regards (and thanks for your patience), Jo