In MyMail, Ltd. v. America Online, Inc., (No. 06-1147, -1172; February 20, 2007), the Federal Circuit affirms the district court's denial of a collateral attack on the ownership of the patent due to fraud. MyMail obtained ownership of the patent by assignment. The assignee obtained the patent application through a state court foreclosure action on a promissory note secured by the application. America Online asserts that the promissory note is fraudulent and this issue is subject to de novo review by federal courts. Distinguishing fraud relating to procurement of a patent, which bears on the enforceability, the Federal Circuit holds that fraud relating to ownership does not affect enforceability and is a state law issue. Since there is an enforceable state court judgment of ownership, that can be challenged only in limited circumstances, fraud in ownership is not subject to de novo review by federal courts.