President Donald Trump's newest pivot might be his way to divert attention from his own Russia troubles by leveling a Watergate-level conspiracy allegation at former President Barack Obama. But this latest assertion that Obama ordered illegal surveillance of Trump Tower during the 2016 election — tweeted without evidence — could build and get the president into some legal hot water. Although the law provides a great deal of leeway for political speech, that protection is not all encompassing. And because of the way Trump has leveled unsubstantiated accusations at Obama, he may have libeled his predecessor. "He's basically stating that...