Promoting Public Safety and Supporting Law Enforcement Act of 2020 This bill directs the Department of Transportation (DOT) to withhold 5% of highway safety program and national priority safety program funding from states and local governments that defund or otherwise reduce funding for a law enforcement entity without a clear budgetary reason. A state or local government may submit documentation or other evidence to DOT for review to determine if the defunding of, or other reduction in funding for, a law enforcement entity was carried out for a clear budgetary reason.