Author John Steinbeck with his son, Thomas in 1963
A US court was wrong to award rights to some of John Steinbeck's best-known novels to his son and granddaughter, an appeals court has ruled.
Thomas Steinbeck and Blake Smyle were awarded the rights in 2006 after a lengthy court battle.
But the appeals court ruled the lower court had misapplied copyright law.
The reversal means the Penguin Group can retain publishing rights to 10 early works by the author including The Grapes of Wrath and Of Mice and Men.
Other Steinbeck books affected by the ruling include Tortilla Flat and the author's first published novel, Cup of Gold.
In 2006, New York District Judge Richard Owen granted the rights to Thomas Steinbeck and Blake Smyle after ruling that heirs could terminate contracts under copyright laws to allow artists or their descendants "appropriate reward for the artistic gifts to our culture".
But while the family members had sought to end a 1938 agreement with Penguin by serving a notice of termination in 2004, that notice was not valid, the US Court of Appeals said.
It said Steinbeck's third wife, Elaine, had entered a new publishing agreement in 1994 , which should be allowed to stand.
When she died in 2003, she left her copyright interests to her children and grandchildren from a previous marriage, excluding Steinbeck's two sons and their heirs.
"We conclude that the 2004 notice of termination is ineffective - the 1994 agreement remains in effect," the three federal appeal court judges wrote.
Steinbeck family lawyer Mark Lee said in a statement they were "disappointed" with this ruling, but planned to continue to pursue damages claims against Elaine Steinbeck's estate and other defendants.
"My clients are still weighing their options with regard to further appellate action," he told Reuters.
Penguin said: "As John Steinbeck's publisher for over 60 years, we are tremendously gratified."
Steinbeck, who set many of his books in his native California, received both a Pulitzer Prize and the Nobel Prize for Literature. He died in 1968.