President Donald Trump and California Gov. Gavin Newsom are clashing over the deployment of the National Guard amid ongoing Los Angeles riots with different interpretations of the 1878 law that governs the use of the military to enforce the law domestically.The Posse Comitatus Act was signed into law by President Rutherford B. Hayes amid concerns that the military had too much sway over civilian affairs during Reconstruction. It generally bars the use of the U.S. military for civilian law enforcement inside the country, but there are key exceptions. Trump deployed the National Guard early Sunday, but so far, those troops