President Trump confronts complicated problems as the investigation widens into Russia’s attack on our political system. But his responsibilities are simple: A month ago, he swore an oath that he would “faithfully execute” his office and “preserve, protect and defend the Constitution of the United States.” That’s apparently easier said than done. In a rambling press conference Thursday and …

  Speculators have piled back into oil since OPEC announced output cuts in November. But don’t be fooled into thinking that means prices are set to soar. As my Bloomberg News colleague Alex Longley pointed out last week, hedge funds and money managers have placed record trades on an oil rally. Net long positions of so-called oil speculators reached an …

  Europe’s promise to lower greenhouse-gas emissions looked bright a dozen years ago, when its leaders created the first big market for trading carbon permits. Sadly, though, its system has failed to encourage investment in clean technology and appreciably lower carbon dioxide emissions. Until the European Union trims the number of permits traded enough to drastically raise the cost of …