Walter Scott Notification Act of 2020 This bill establishes new requirements for existing grant programs to incentivize reporting on deadly shootings by law enforcement. Specifically, it requires a state that receives funding under the Edward Byrne Memorial Justice Assistance Grant (JAG) program to report certain data on deadly shootings by law enforcement officers. It reduces by 10% the JAG allocation of a state that fails to comply. Additionally, for an initial four-year period, the Department of Justice (DOJ) may give preference to a Community Oriented Policing Services (COPS) program grant applicant from a state that reports data on deadly shootings by law enforcement. Beginning in the fifth year, DOJ must reduce by 20% the COPS allocation of a state that fails to report such data.