judges black cap why?

Question

why did a judge place a black cap on his head before passing the death sentence

Answer 1

I have found several sources which say that a judge donning a black cap is a sign of mourning:

"The judge puts on his black cap (now a three-cornered piece of black silk) when he condemns to death, in sign of mourning. This sign is very ancient. “Haman hasted to his house mourning, having his head covered”.
http://www.bartleby.com/81/9338.html

It is reiterated here:

"This is because covering the head has from the earliest times been regarded as a sign of mourning. Numerous examples of this occur in the Scriptures, in the classics, and in modern literature. "The ancient English," says Dudley Fosbrooke, in his monumental work on archology, "drew their hoods over their heads at funerals."
http://www.sacred-texts.com/etc/mco/ml08.htm

Another reason is that the black cap forms part of the full dress of a judge, which is worn only on extraordinary occasions. When the new Lord Mayor is presented in the Court of Exchequer on the 9th of November, the judges receive him with their heads so covered.
(Source as above)

Black, as you know, is the colour of death.

Answer 2

It was supposedly to protect the Judge from the wrath of God whilst handing out the Death sentence, as it was believed (in Victorian times) that it was only for God to decide who should live or die.

Answer 3

The other two answers are basically right. It denoted to the prisoner that a death sentence was about to be passed.

Answer 4

because black is the colour of death

Answer 5

To frighten the sh*t out of the accused!