US judge rules shale oil antitrust case can proceed against major producers ↧ ↧ US judge rules shale oil antitrust case can proceed against major p... Diamondback Energy , Occidental Petroleum and several other U.S. oil producers failed to persuade a federal judge to dismiss a series of lawsuits alleging ​they conspired to curb output, leading to higher prices for crude oil ‌and related products such as gasoline, diesel fuel and home heating oil.