In Leiningen 2.x, if a jar is used and isn't in a remote Maven repo, then it needs to be in the local Maven repo. This is useful for native OS-specific jars, for example. The fully-worked out solution as it relates to Leiningen 2.x is explained in my post, here:

http://www.elangocheran.com/blog/2013/03/installing-jar-files-locally-for-leiningen-2/