The most common question about false convictions is also the simplest: How many are there? The answer, unfortunately, is almost always the same, and always disappointing: We don’t know. Recently, however, we have learned enough to be able to qualify our ignorance in two important respects. We can put a lower bound on the frequency of false convictions
among death sentences in the United States since 1973, and we have some early indications of the rate of false convictions for rape in Virginia in the 1970s and early 1980s. These new sources of information suggesttentatively-that the rate of false convictions for serious violent felonies in the United States may be somewhere in the range from 1%–5%. Beyond that-for less serious crimes and for other countries-our ignorance is untouched.