"Beyond any doubt" would mean abolishing it. It is an impossible standard
Any case held to the standard of "beyond any doubt" would be trivially defended. It is theoretically possible we're all in the matrix and the whole case was just faked by our all-powerful machine overlords. Is the doubt reasonable? No. Is it a doubt? Yes
I'm in favor of abolishing the death penalty. We shouldn't do it with roundabout semantics and sham trials though
Are there test kits that could differentiate the two? Wouldn't they both just test positive for amphetamines?
Or are you suggesting it to check for other drugs such as fentanyl?