Chief Justice John Roberts has led the Supreme Court’s conservative majority on a steady march of increasing the power of the presidency. And that began well before Donald Trump’s time in the White House. The justices could take the next step in a case being argued Monday that calls for the overturning of a unanimous 90-year-old decision that limits executive authority. The court’s conservatives already have allowed Trump to fire almost everyone he's wanted to in his second term. That's despite the court’s 1935 decision that prohibits the president from removing the heads of independent agencies without cause.