Benjamin J. Keele has self-archived "Examining Law Journal Publication Agreements for Copyright Transfers and Self-Archiving Rights" in SSRN.
Here's an excerpt:
This study examines 78 law journal publication agreements and finds that a minority of journals ask authors to transfer copyright. Most journals also permit author to self-archive articles with some conditions. The study recommends journals make their agreements publicly available and use licenses instead of copyright transfers.