If you have been vaccinated for polio, mumps, measles, chicken pox, hepatitis, or rabies, it may be too late for you to stand your ethical ground: You have already benefited from fetal-tissue research. This is, after all, a practice that's been legal since the 1930s.

A dog that has rabies probably will do things it wouldn't do if it didn't have rabies. But that doesn't change the fact that it has rabies.