In United States v. Santana, 342 F.3d 60, 68 (1st Cir. 2003), cert. denied, 540 U.S. 1206 (2004), the appellant alleged, inter alia, that it was error for the district court to allow the testimony of a DEA agent that the agent could smell marijuana because it was not lay opinion testimony under Federal Rule 701; rather, it was an expert opinion.
The United States Court of Appeals for the First Circuit disagreed.
It is axiomatic that a witness may testify as to his personal knowledge - here, what he smelled. There was a sufficient foundation for this testimony because the DEA agent testified that his job exposed him to marijuana, and another witness testified that marijuana residue was found on the wrapper . . . . However, the DEA agent's testimony as to what he smelled was based on his perception and therefore he was not required to qualify as an expert under Rule 702. It was not an abuse of discretion to admit the DEA agent's lay opinion testimony that the smelled marijuana during a search of Nickerson's home. (Id. at 68-69.)