Does the Statute of Frauds prevent enforcement of Mills’s promise?

Barbara Sawyer, a paralegal, worked for attorney Melbourne Mills, assisting him in a class action lawsuit against the makers of a popular diet drug called Fen-Phen. Mills promised Sawyer a large bonus “when the ship comes in,” but he never specified how much he would pay her. Mills successfully settled the Fen-Phen case for millions of dollars, and he later met with Sawyer and her husband to discuss her bonus. The Sawyers secretly recorded the conversation.
The Sawyers asked Mills for a $1 million bonus, to be paid as a lump sum. Mills refused. However, the parties kept talking and Mills eventually agreed to pay Sawyer $1 million, plus $65,000 for a luxury automobile. Payments were to be made in monthly installments of $10,000, for 10 years. Mills also agreed to sign a document confirming his promise. Sawyer’s lawyer drafted the writing, but Mills never signed it. He did pay nine monthly installments, along with an extra payment of $100,000.
At trial, jurors heard the tape recording, which confirmed the oral agreement. The jury concluded that the parties had reached a binding agreement and awarded Sawyer $900,000. However, the court granted a judgment notwithstanding the verdict for Mills. He ruled that the agreement was barred by the Statute of Frauds. Sawyer appealed.