Sara R. Benson and Hannah Stitzlein have published "Copyright and Digital Collections: A Data Driven Roadmap for Rights Statement Success" in ACRL 2019 Proceedings.
Here's an excerpt:
The two questions that ultimately guided this research were: What are the challenges that metadata practitioners face when implementing standardized rights statements? And, for institutions that have implemented standardized rights statements, what made them successful? The authors began the investigation to fill in the practical gaps of the previous studies, and to determine if barriers to implementing standardized rights statements was due to a lack of copyright knowledge and/or access to a copyright professional, or if there were resource barriers limiting the ability to begin implementation.