Legal Question in Criminal Law in California

"Peer" does not mean "someone who is very much like the defendant." Instead, it means someone chosen more-or-less at random from the same region. Defendants are entitled to jurors who are selected fairly from a pool that is chosen in non-discriminatory ways. That does not mean the jurors who end up on a given case will be like the defendant. The jury can't be tailored to exclude people who are like the defendant, but it also can't be tailored to exclude people who aren't.

Your question considers only the defendants' ethnicity. But even if you see people only as members of groups rather than individuals, ethnicity is just one of many ways to categorize them. They could also be grouped by religion, gender, age, socioeconomic status, etc.

Let's say a defendant is a middle-aged, liberal, Asian, female, Buddhist, gay, college-educated, overweight, non-smoking, physically disabled retiree. She is not entitled to a jury of twelve other middle-aged, liberal, Asian, female, Buddhist, gay, college-educated, overweight, non-smoking, physically disabled retirees. Imagine how hard it would be to find twelve such people in a jury pool. For that matter, imagine how hard it would be to find twelve who are young, conservative, white, male, Christian, and straight. Even finding twelve who are white, male, and Christian would require dismissing dozens of other potential jurors. And if a case had multiple defendants who weren't members of all the same groups, it would be literally impossible to give each of them 12 jurors like themselves.

Besides, who's to decide how to even draw these categories? Where some people see one category of Christians, others see Protestants, Roman Catholics, Eastern Orthodox, etc. Where some see one category of Protestants, others see Episcopalians, Lutherans, Baptists, etc. Similarly, where some see only Asians, others see Chinese, Japanese, Korean, etc. And where some see only Chinese, others see Han, Hui, Tibetan, etc. (And there is lots of room to disagree about whether Tibetans should be counted as Chinese at all.) So there would be insurmountable line-drawing problems even in a system that worked the way you suppose.

Imagine how such a system would play out. Could a court justly exclude jurors based on their race, ethnicity, sex, religion, etc.? "Juror No. 12, you're excused because your skin is the wrong color." Our courts do not work that way.

The fact that those two Hispanic defendants had a mostly-white jury does not mean their rights were violated. Unless the prosecutor or the courts tilted the playing field against Hispanics, I don't see an issue.

The US Supreme Court has ruled that lawyers cannot use race as a consideration in picking jurors. For example during voir dire in this case four Hispanics are questioned and the DA excludes every one of them without good cause the Hispanic defendants have a right to disqualify the jury and start over. Likewise say the defense attorney feels that African Americans should not sit on this jury and excuses every African American based solely on race the DA can ask for a mistrial.