"Chief Justice William H. Rehnquist, writing for the court, said the former Big Five accounting firm's obstruction-of-justice conviction was improper because the instructions at trial were too vague for jurors to determine correctly whether Andersen obstructed justice.

"The jury instructions at issue simply failed to convey the requisite consciousness of wrongdoing," he wrote. "It is striking how little culpability the instructions required."

Enron crashed in December 2001, putting more than 5,000 employees out of work, just six weeks after the energy company revealed massive writedowns. As the Securities and Exchange Commission began looking into Enron's convoluted finances, Andersen put in practice a policy that called for the destruction of what it considered unnecessary documentation.

Government attorneys then went after Andersen, making it the first major prosecution in the wake of the Enron scandal, citing the firm's "unprecedented campaign of document destruction." They said Andersen was guilty under an obstruction law that made it a crime to "corruptly persuade" others to destroy documents.

In his opinion, Rehnquist said it is not necessarily wrong for companies to instruct employees to destroy documents. At trial, Andersen argued that employees who shredded tons of documents followed the policy and there was no intent to thwart the SEC investigation.

Like a mother who advises a son to invoke his right against compelled self-incrimination out of fear he might be convicted, "persuading" an employee to withhold information is not "inherently malign," Rehnquist wrote.

Legal experts said the ruling, which was widely expected, will shield former partners at Andersen from possible future litigation. Corporations that have document-retention policies also will have more freedom to destroy documents without fear of potential prosecution."

I wish someone could explain this to me. The above paragraphs are from the Washington Post this morning. I read them but I still do not understand why the conviction was overturned. Seemed like obstruction of justice, to me, all the massive shredding of documents all at once, in unprecedented amounts and short deadlines. I seem to remember hearing they had to hire special trucks to pick up and dispose of the shreds. Do they have to prove intent for it to be obstruction?