[JamesP81]

The prosecution should be under no burden to prove that every defendant that comes to court isn't retarded.

That's a determination for the jury to make, not the black robes. If a defendant who is mentally competent claims he is retarded, I trust the common man sitting on the jury far more than the black robes to make the determination as to the defendant's honesty. The method of defense a defendant uses is not subject to state approval. Ever. That would be like the US using only methods of fighting wars that her enemies deem appropriate, or only building a wall on the southern border if Mexico approves it. Oh wait...

[L98Fiero]

"That's a determination for the jury to make, not the black robes."

Exactly. First sentence in the article.