My focus is on an apparent trend at the intersection of the fields of evidentiary standards for expert admissibility and professional responsibility, namely the eagerness to place more ethical responsibilities on lawyers to vet their proffered expertise to ensure its reliability. My reservations about this trend are not only based on its troubling implications for the lawyer’s duty as a zealous advocate, which already has obvious limitations (because of lawyers’ conflicting duties to the court), but are also based on the problematic aspects of many reliability determinations. To expect attorneys – and this is what the proponents of a duty to vet experts expect – to do sufficient scientific research to create their own reliability controversy, make a determination as to the ultimate reliability of their own experts, and face ethical sanctions if they err is going too far. While it is easy to choose examples that support a compelling argument for a responsibility to vet experts, the complexity of the scientific enterprise, in terms of its diverse methodologies, probabilistic conclusions, and genuine scientific disagreements, counsels against a broad, new ethical duty. Indeed, some of the arguments for that new duty seem to rest on unrealistic assumptions about science and the ease with which reliability determinations can be made. Moreover, a broad duty to vet experts would represent a serious and problematic departure from the lawyer’s role as an advocate.