Mary Frances Allen v. Commissioner

Mary Frances Allen (plaintiff) wore a valuable brooch to the Metropolitan Museum of Art, noticed at 4:30 p.m. that it was still pinned to her dress, and discovered by 5:00 p.m. — amid a crowd of about 5,000 people — that it was gone. She did not see how it disappeared and offered no evidence about the clasp's security, whether she had bumped into anyone, or whether her dress showed any damage from the pin being removed. She sought to deduct the brooch's value as a theft loss, and the Commissioner (defendant) disallowed the deduction.