The U.S. Supreme Court has overturned the conviction of the Arthur Andersen accounting firm for destroying documents related to its Enron Corp. account before the energy giant’s collapse.

In a unanimous opinion, justices said the former accounting firm’s June 2002 conviction was improper. It said the jury instructions at trial were too vague and broad for jurors to determine correctly whether Andersen obstructed justice.

“The jury instructions here were flawed in important respects,” Chief Justice William H. Rehnquist wrote for the court.

Enron crashed in December 2001, putting more than 5,000 employees out of work, just six weeks after the energy company revealed massive losses and write-downs.

Subsequently, as the U.S. Securities and Exchange Commission began looking into Enron’s convoluted finances, Andersen put in practice a policy calling for destroying unneeded documentation.

Government attorneys argued that Andersen should be held responsible for instructing its employees to destroy documents.