The Official Jessup Rules require teams to identify their sources in their Memorials (written submissions). The Rules also require teams to use a citation form that provides a description of each authority that is adequate enough to allow a reasonable reader to identify and locate the authority in a publication of general circulation.
The Bluebook is one of 4 citation systems that the ILSA Executive Office recommends (the other 3 are: Canadian Guide to Uniform Legal Citation;
The Oxford Standard for Citation of Legal Authorities; Introduction to Basic Legal Citation - links to each are on the Competition's website under the "team resources" tab).