https://law.temple.edu/aer/2019/06/19/expert-or-lay-opinion-where-is-the-line/
“The DNA profile from the crime scene shares the same alleles as the DNA from the accused.” That is a statement of fact or an expert opinion, but whatever it is it is not lay opinion. “I ride bicycles a lot. When the brake pads start to wear down, it’s riskier to ride in the rain.” Now, what is that? Expert or lay opinion? And why do we care? Because to proffer expert opinion ...