[binarybits]

There's also a countervailing bias that I suspect is far more important: most wrongly-convicted defendants have no way to prove their innocence, and so we never learn that they were wrongly convicted. Many criminal defendants are not sophisticated about the law, and their cases are handled by overworked public defenders. The courts in many states are extremely stingy about giving defendants access to evidence or legal appeals post-conviction. So even if potentially-exculpatory evidence emerges, the convict often can't do anything with it.

This is one of those statistics that will never be known with any precision, but even if the number of known exonerations is small (which I don't know to be the case) that doesn't prove that the number of innocents in jail is small.