Werner Siebenmann (defendant) sold a painting to David Rogath (plaintiff) for $570,000. Siebenmann warranted in the sale contract that the painting was an authentic self-portrait by Francis Bacon, and that he did not know of any challenges to the painting’s authenticity. However, Siebenmann claimed that he informed Rogath about a potential challenge to the authenticity from an art gallery in London before Siebenmann and Rogath entered into the sale contract. Subsequently, Rogath sold the painting to a third party, but the third party returned the painting after it discovered a challenge to the painting’s authenticity. Rogath accepted the returned painting and brought suit against Siebenmann for breach of warranty, among other things, in the United States District Court for the Southern District of New York. The district court granted Rogath’s motion for summary judgment on the breach of warranty claim. Siebenmann appealed.