In a ruling that’s a history lesson as much as a breach of contract decision, the U.S. Court of Appeals for the Fifth Circuit found that JP Morgan Chase Bank must assume the leases of the failed Washington Mutual Bank it bought for $1.8 billion. To rule otherwise, the court concluded, would return Fifth Circuit landlord/tenant law “to that of twelfth-century England.”

The background to the Fifth Circuit’s Jan. 10 decision in Excell Willowbrook v. JP Morgan Chase and Federal Deposit Insurance Corp. is as follows.