Donald Trump turned himself in Tuesday for a historic New York court hearing held amid tight security and a global media frenzy, as the Republican billionaire becomes the first American president in history to face criminal charges. In a spectacle playing out on live television - with rival protesters rallying outside -- the hearing marks a watershed moment for the US criminal and political system, with the potential to upend the 2024 White House race in which Trump is currently the presumptive Republican nominee.