US Criminal law has a long long history of reliance on scientifically invalid forensic evidence. Bite marks, fingerprinting, fiber analysis, breathalyzers, hypnosis and others have all been legally ruled to be beyond reproach at various times/places, and all of them are on a continuum of scientific reliability ranging from laughable through potentially useful for some purposes if properly performed and evaluated.(Hypnotizing witnesses is still legally valid in Texas and some other places.)

If "beyond a reasonable doubt" is supposed to mean something, then it should mean something.

And by the way, eyewitness testimony is frequently really unreliable.