Open Linked Data versions of work-level bibliographic records for a large number of legal publications appear to be available as part of OCLC WorldCat Works, which was announced on 28 April 2014: OCLC releases WorldCat Works as linked data.
Data appear to be available in the following formats:
One can view Linked Data available for a particular publication, by displaying an OCLC WorldCat record, scrolling to the end, and clicking “Linked Data.” See, e.g., this record for a recent edition of Chitty on Contracts, a treatise on British contract law that has been published in many editions.
The data are licensed under an Open Data Commons Attribution License.
The data appear to include records for both primary and secondary legal resources.
In terms of primary legal resources, here is a human-readable display of OCLC work-level Linked Data for the UK Copyright Act 1956: http://experiment.worldcat.org/entity/work/data/1151695652.html
In terms of secondary legal resources, here is a human-readable display of OCLC work-level Linked Data for a recent edition of Chitty on Contracts: http://experiment.worldcat.org/entity/work/data/19959762.html