In setting up a data access policy to share controlled access data from the McGill Epigenomics Mapping Centre (EMC), an International Human Epigenome Consortium (IHEC) partner project, we encountered ethical and legal challenges that are likely to be relevant to other researchers sharing data, especially from Canadian projects. We discuss our solutions to the following data-sharing challenges, based on comparative legal and policy analysis: (1) providing access to data to a growing number of researchers; (2) maintaining Canadian privacy standards while sharing controlled access data internationally; (3) freedom of information requests; and (4) providing more incentives for researchers to share pre-publication data.