Recent events have turned public attention to the previously obscure Militia Act of 1903 and the even more obscure historians and political scientists interested in eighteenth- and nineteenth-century insurrection law. President Donald Trump claimed that the measure vests him with the power to federalize members of the California National Guard to curb what he claims is a rebellion by persons protesting U.S. Immigrant and Customs Enforcement activities in Los Angeles or an uprising that is pre...