They bar trademark protection.
Victoria Panettiere 24, JD candidate at GW Law School, BS from Northeastern, “The Green Wave and Potential Impacts on Federal Trademark Eligibility,” Federal Circuit Bar Journal, 33(2), pp. 183-184, Lexis, kav
Despite rapid state-level efforts toward legalization, the federal cannabis prohibition presents a major problem for businesses in the industry seeking federal trademark protection.91 To avoid being barred from federal trademark protections, these businesses must either jump through major hoops to ensure compliance with federal law or settle for less rigorous protections under state [*184] trademark law.92 These limited options not only depress the industry but also cause harm to consumers, cannabis farmers, and business owners while directly conflicting with the purposes of federal trademark law.93