BP Alaska Spill 2006
BP Exploration president Steve Marshall holds up a picture of the 2006 oil spill during a Senate Energy Committee hearing in September 2006. This week, the company has been relieved of its probation period. Reuters

A federal judge in Anchorage Tuesday terminated BP Exploration's probation years after an oil pipeline rupture took place this past decade.

The dismissal also quieted claims made by U.S. prosecutors that the British company's Alaskan subsidiary violated the terms of its probation, which was the subject of a court hearing in recent weeks.

According to prosecutors, BP violated its probation after a pipeline in 2009 ruptured in Alaska's North Slope. It was the company's second pipeline accident in three years, and according to court documents, prosecutors argued the company was criminally negligent for allowing the second rupture and the spilling of 13,500 gallons of oil to take place.

Judge Ralph R. Beistline, however, did not see it that way, and sided with BP, which maintained its engineers could not have predicted the rupture, or had any previous reasons to suspect the pipeline was about to fail.

The investigation concluded, based on the metallurgy report, that the pipeline rupture was not caused by corrosion or improper maintenance, but was caused by a sequence of circumstances, including cooling and warming of ambient temperature after the flow stopped, which led to the freezing of both water and hydrates, wrote Beistline in his ruling reported the Associated Press.

This ultimately resulted in increased gas pressure within the pipeline that caused the rupture, Beistline added. Why the flow slowed initially remains a mystery to all.

BP was placed on probation for three years in 2006 after one of its pipelines corroded and ruptured spilling 200,000 gallons. BP pled guilty to that incident in 2007, but has had to wait more than four years since then to argue its case in court, at a time when BP faces increased scrutiny in the U.S. following the millions of barrels of oil it spilt in the Gulf of Mexico.