PACER holds billions of pages of documents associated with cases before federal courts. It is not appropriate for historical research but invaluable for recent and pending cases. PACER requires the creation of an account. It is not free but limited research should not accrue a charge. Your liaison librarian has a PACER account. He can demonstrate how to use it but will not conduct research for students, faculty, or staff.
This guide is heavily inspired by the organization and observations of Paul D. Healey, whose work Legal Reference for Librarians is an invaluable resource.