Getchell v. Lodge
In Getchell v. Lodge, 65 P.3d 50 (Alaska 2003), the court noted that "experts" -- i.e., witnesses who have specialized training, education, or experience -- will sometimes give testimony that is partially based on their own personal observations, and partially based on their expert analysis that is, conclusions that the witness drew from these factual observations based on the witness's specialized training, education, or experience.
The court employed the term "hybrid" witness to describe this situation.
The supreme court's analysis in Getchell rests on the recognition that certain types of experts (for example, doctors and nurses) are often called to testify about things that they personally observed, and also to offer their expert opinion about the meaning of those observations. These witnesses are giving "lay testimony" to the extent that they are describing the events, conditions, or circumstances they personally observed, and they are giving "expert testimony" to the extent that they are offering an explanation or analysis of these observations based on their expertise.