Once one of the biggest and most powerful oil companies in the world, BP faces years more of uncertainty that will put continued pressure on shares and may open the company to takeover pressure from larger rivals such as Royal Dutch Shell Plc or Exxon Mobil Corp.

Today’s ruling defines the scope of the ultimate payouts, which will be determined after a trial scheduled to begin in January 2015 in New Orleans. If Barbier agrees with the government’s spill estimate of 4.2 million barrels, the payout could ultimately be as high as $18 billion based on federal guidelines for pollution fines. If he sides with BP’s estimate that only 2.45 million barrels spilled, it would reach $10.5 billion.

Barbier has discretion in how the fines are ultimately decided. “During the penalty proceedings, BP will seek to show that its conduct merits a penalty that is less than the applicable maximum after application of the statutory factors,” BP said in its statement.

BP also may be subject to unspecified punitive damages from lawsuits. Legal appeals may prolong the outcome for more than a decade -- Exxon paid the final punitive damages from the 1989 Valdez spill off Alaska 20 years after the incident.

Eoin Treacy's view

BP failed to sustain the breakout to new highs in late June and encountered resistance this week in the region of the 200-day MA. The next area of potential support is in the region of 425p but a clear upward dynamic will be required to check momentum beyond a brief pause.