Should black people in the US receive longer prison sentences?

Men receive longer prison sentences than women for exactly the same crimes. The rationale given for this by judges and the State is that women commit far fewer crimes, and therefore there is less need for deterrent.

In the US, roughly 40% of all prison inmates are black, despite making up only 15% of the general population. By the year 2020, at current rates of incarceration, more than 2 out of every 3 black males in the US will have spent time in the penal system. Given that black men are therefore disproportionately likely to be caught and convicted of a crime, I have a modest proposal. Does it not make sense that black men should be given longer sentences for the same crimes in order to create a deterrent?

We would have to be scrupulously fair, of course. We could use scientific instruments to determine the Angstrom range of the surface of the convict’s skin, then use a simple multiplier based on the darkness of the skin to increase the sentence length. The contrary would also hold of course, in which the lightness of a convict’s skin would serve to decrease the overall prison stay, since white people seem to need less deterrent.

(Fortunately the State is way ahead of us. With the wisdom of Solomon, they have been giving black people longer prison sentences for some time now, even without any formal legal doctrine.)