The court on Monday said it will leave in place a ruling by the Virginia Supreme Court that the law was unconstitutional because it prohibited political, religious and other messages in addition to commercial solicitations.
Virginia was the only state to ban noncommerical spam e-mail.
The decision also cements the reversal of the conviction of Jeremy Jaynes, who once was considered one of the world's most prolific spammers. Jaynes bombarded Internet users with millions of pieces of spam, all of it commercial.
In 2004, Jaynes became the first person in the U.S. to be convicted of a felony for sending unsolicited bulk e-mail. He was sentenced to nine years but is currently serving time in federal prison on an unrelated conviction for securities fraud.
The case is Virginia v. Jaynes, 08-765.