In February 2002, Lucas Riley (plaintiff) was in the process of turning from a local road onto U.S. Highway 63 in Missouri. Visibility of Highway 63 was compromised by mailboxes. Believing the road to be clear, Riley pulled onto the highway. His vehicle was broadsided by a truck, resulting in serious injuries. Riley sued the United States (defendant) on the ground that the United States Postal Service (USPS) had negligently placed the mailboxes. Residents in the area had complained about the location of the mailboxes in the past, but the USPS declined to move them on account of cost. After Riley’s accident, the USPS agreed to relocate the mailboxes. In its defense to Riley’s suit, the United States offered evidence that the USPS had decided to locate the mailboxes curbside for purposes of efficiency and safety given that many homes were set far back from the roadway. A federal district court dismissed Riley’s complaint on the basis of sovereign immunity. Riley appealed.