Ronald Biles (plaintiff) claimed that he was injured from exposure to asbestos while helping build an oil refinery. Biles sued Exxon Mobile Corp. (Exxon) (defendant), the eventual owner of the refinery, for premises liability. During discovery, Exxon served an interrogatory asking Biles to identify each person who knew something about the work exposing Biles to asbestos. In May 2003, Biles answered the interrogatory by stating that he had conducted a reasonable inquiry and did not have information responsive to the request. Biles also reserved the right to supplement the response as his investigation continued. Exxon moved for summary judgment based on a lack of evidence that Biles had been exposed to a dangerous condition. The same law firm that represented Biles also represented different plaintiffs in a separate asbestos case against Exxon. A witness deposed in that separate case, Roger Bellamy, testified that he had worked with Biles at the same oil refinery. When Biles responded to Exxon’s motion for summary judgment, he relied on: (1) Bellamy’s deposition testimony from the separate case and (2) a declaration from Bellamy saying that Exxon employees used compressed-air hoses to blow asbestos dust throughout the refinery. Exxon objected to this evidence because Bellamy had not been disclosed in either the original interrogatory response or in any supplemental interrogatory response as someone with information about Biles being exposed to asbestos at work. The trial court agreed, based in part on a finding that Biles had promised to supplement the interrogatory response if he uncovered new information, and excluded the evidence from Bellamy. The trial court then granted Exxon’s motion for summary judgment. Biles appealed.