Still, that alternate confession must be credible. For high-profile crimes, there often seem to be dozens of alternate confessions, and they are usually obvious

Still, that alternate confession must be credible. For high-profile crimes, there often seem to be dozens of alternate confessions, and they are usually obviously untrue so they should not be grounds for appeal of the convicted. The hard part is how to establish that alternate confessions or new evidence are really significant (as they indeed sometimes are).