May 31 (Bloomberg) -- The U.S. Supreme Court overturned accounting firm Arthur Andersen LLP's conviction for obstructing a government investigation into Enron Corp., dealing a unanimous rebuke to the Bush administration's corporate-fraud crackdown.

The court today said the jury instructions didn't require prosecutors to show that Andersen officials acted dishonestly in urging employees to shred documents connected to the firm's audits of Enron, an energy trader that collapsed after an accounting fraud.

The instructions ``simply failed to convey the requisite consciousness of wrongdoing,'' U.S. Chief Justice William H. Rehnquist wrote for the court in Washington.

The decision almost certainly comes too late to help Andersen, which was once the world's fifth-largest accounting firm. The Chicago-based firm no longer conducts public audits and now has only 200 employees, mostly lawyers and administrators.

Andersen spokesman Patrick Dorton said he didn't have any immediate comment.

The high court decision didn't specifically rule out the possibility of a new trial, although criminal-law experts previously said that was unlikely.

The high court acted with unusual speed, issuing its decision barely a month after hearing arguments.

Shredding Documents

Andersen was accused of persuading its employees to purge and shred company records just as the U.S. Securities and Exchange Commission was preparing to open a formal investigation into Enron's accounting. Prosecutors opted not to charge Andersen for the document destruction itself.

Andersen said it was merely reminding employees of its longstanding ``document-retention policy,'' which called for elimination of duplicates, drafts and notes once an audit was complete.

That type of policy is ``common in business,'' said Rehnquist, who announced the decision from the bench.

``It is, of course, not wrongful for a manager to instruct his employees to comply with a valid document retention policy,'' he wrote.

The case is Arthur Andersen v. United States, 04-368.

To contact the reporter on this story: Greg Stohr in Washington at gstohr@bloomberg.net.

Last Updated: May 31, 2005 10:53 EDT