In the latest—and perhaps final—round of a bitter battle for a control of the John Steinbeck literary estate, a three-judge panel of the U.S. Second Circuit Court of Appeals this week affirmed an earlier dismissal of claims brought by Steinbeck’s son, Thomas Steinbeck, against the heirs of the great American author’s third wife, Elaine Steinbeck, and literary agency McIntosh & Otis.

In its decision, the court affirmed a lower court’s dismissal of Steinbeck’s claim, which charged breach of fiduciary duty. A charge of unjust enrichment was also dismissed. The case began after Elaine Steinbeck’s 2003 death and bequest passing on control of her estate, including control of John Steinbeck’s copyrights, to her children from a previous marriage. John Steinbeck died in 1968. Thomas Steinbeck had previously signed over power of attorney to Elaine Steinbeck in an attempt to resolve a previous dispute.

In a statement, attorney Jennifer Ancona Semko said Thomas Steinbeck and his family were “deeply disappointed with the ruling and are considering their next move.”