CITES, the Convention on International Trade in Endangered Species, in appendix 2, has a genus-wide restriction on all Dalbergia species including Cocobolo, Dalbergia retusa. It is also listed on the IUCN, the International Union for Conservation of Nature, Red List as vulnerable due to a significant decrease in its population (deforestation and exploitation). In addition to Cocobolo, some of the other familiar Dalbergia species are Tulipwood, Kingwood, and African Blackwood.
Neither of these completely ban import and export, but it does require obtaining special permits and documentation. Some specific species are limited farther such as Brazilian rosewood. Australia strictly enforces the CITES regulations so importers are required to provide their CITES import permit and other documentation that proves that the timber was legally sourced. I'm guessing for lower volume, lower consumption timbers, most importers have simply chosen to forego all of the permits, licensing and other documentation required.
Every year it seems like CITES adds more familiar pen blank species to their Appendix. For example, last year, 2024, Brazilian walnut, (Ipe) and Brazilian teak (Cumaru) were also added to CITES Appendix 2. In 2023 it was African mahogany and African rosewood.
Dave