Juries are to be impartial and decide only upon the evidence that is put forth by the prosecutor and defendant as it relates to the charges and the law that defines those charges. If a juror states up front that they'll vote one way or another, without hearing the evidence, based on some prejudice then they will be disqualified.
But selecting juries based on that trait (or any trait for that matter) is in direct conflict with one's right to trial by a jury of his peers (presumably defined as the general populace). Once you predicate the selection process, you skew a uniform sampling of "peers" and the jurors selected are no longer representative of one's "peers".
The "jury of your peers" concept isn't part of United States law at all. It is a part of British Common Law, but the governing rule in the US is the Sixth Amendment of the Constitution of the United States, which provides only for "an impartial jury of the State and district wherein the crime shall have been committed".
The "jury of your peers" language, whose origin is the Magna Carta [1], is included in the constitutions of a number of states, so the concept directly pertains in many American jurisdictions.
There is also a considerable body of federal case law applying the equal-protection clause of the Fourteenth Amendment to the process of jury selection. Since 1880, when the U.S. Supreme Court overturned a black man's conviction for murder due to the systematic exclusion of blacks from local juries [1], federal courts have consistently ruled that jurors must be selected indiscriminately from eligible members of the community. This is very close to the concept of a "jury of your peers".
It's called impartiality and is the notion that you should be judged based only upon objective criteria that is delivered by your accuser. In the US, impartiality is guaranteed by the 6th Amendment. Note, that the US Constitution does not say anything about a "jury of peers."
