"The US government has lost billions of dollars of oil & gas revenue to fossil-fuel companies because of a loophole in a decades-old law-- the first detailed accounting of the consequences of a misstep by lawmakers that is expected to continue costing taxpayers for decades to come. The loophole dates from an effort in 1995 to encourage drilling in the Gulf of Mexico by offering oil companies a temporary break from paying royalties on the oil produced. However, the rule was poorly written, the very politicians who originally championed it have acknowledged, and the temporary reprieve was accidentally made permanent on some wells."