The Supreme Court will take up former President Donald Trump’s “absolute immunity” defense this week‚ and a favorable ruling could nullify many of the criminal charges against him. The case is groundbreaking. No other former president has been in Mr. Trump’s situation or asserted protection from prosecution for actions while in office. Mr. Trump has asked the justices to dismiss a federal indictment accusing him of a conspiracy to subvert the 2020 election. He faces another federal...