(Reuters) -A federal appeals court on Tuesday overturned a judgment requiring IBM to pay rival BMC Software $1.6 billion, after a judge found IBM improperly replaced BMC's mainframe software at AT&T with its own.

The 5th U.S. Circuit Court of Appeals in New Orleans said a lower court judge's determination concerning liability was in error. Writing for a three-judge panel, U.S. Circuit Judge Edith Jones said AT&T, one of BMC's biggest clients, had switched to IBM software "independently" and that BMC had "lost out to IBM fair and square."