In 1946 an American doctor named Jones was tried in Ohio for performing six illegal abortions (State v. Jones, 80 Ohio App. 269). In one of the six cases, the only evidence was the testimony of the woman herself, Jacquelin Harris. But under Ohio law, the recipient of an abortion was an accomplice to the crime, and the unsupported testimony of an accomplice was suspect and insufficient for a conviction.

This means trouble:

• The prosecution can argue that if the doctor is guilty then he should be convicted, and that if he’s innocent then the woman is not an accomplice and her testimony is sufficient to convict him. Either way, he should be convicted.
• The defense can argue that if the doctor is innocent then he should be acquitted, and that if he’s guilty then the woman is his accomplice, which makes her testimony insufficient for a conviction. Either way, he should be acquitted.

“This puts the jury in a position of returning a self-annulling verdict,” writes Peter Suber in The Paradox of Self-Amendment. “If they find Jones guilty, then they must find that Harris was his accomplice, then they must find her evidence against Jones insufficient, then they must acquit Jones. But if they find Jones innocent, then they must (at least may) find Harris’ evidence legally sufficient, then they must (at least may) convict Jones.”

Jones was found guilty, ironically because, as an accused party, he was presumed innocent, and so the witness was presumed not to be an accomplice. “This led to the remarkable situation that the testimony was admissible and could lead to a conviction,” writes Michael Clark in Paradoxes From A to Z, “notwithstanding the fact that the conviction undermined the probative value of the testimony.”

See Turnabout.