Mark Byron says he doesn't know where the need for juries to order the death penalty came from. Actually, this seems pretty straight forward t me. The Sixth Amendment says:
No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a grand jury, except in cases arising in the land or naval forces, or in the militia, when in actual service in time of war or public danger; nor shall any person be subject for the same offense to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation.
The Sixth clearly demands a jury for criminal trials. I don't think that demand ends once the guilty verdict has been reached, especially when you consider the demand for due process. Of course, if you use my logic, imprisonments aren't allowed under the Constitution either. I've not read the SCOTUS opinion, but I don't think it's an unreasonable decision in principle.
Oops. Dr. Byron pointed out to me that I was looking at the Fifth, not the Sixth. I don't know what I was thinking.