Why are Judges (at least at the trial level) DAs in black?
In California the trend probably began in earnest in 1986, when three Justices on the State Supreme Court had their confirmations voted down by the voters (in California, Appeals Judges and Supreme Court Justices must periodically be confirmed by the electorate in an up or down vote, generally a rubber stamp until that time). While the popular source of anger was aimed at these Justices extremely high rate of overturning death penalty sentences (something like 59 out of 60 sentences overturned for some reason or another), the impetus for the anti-confirmation vote was really from big business interests who didn't like the overly friendly views towards consumers that the Justices exhibited. But, the Bird saga (the Chief Justice was Rose Bird, she and two other justices lost their jobs in the vote) has had strong recriminations in the state.
The governor at the time was a law and order Republican named George Dukemeijian (sorry Duke if I spelled it wrong), who had replaced Jerry Brown in 1982. He served until 1990, when replaced by (formerly moderate) Republican Pete Wilson, who discovered the art of demonization to stay in power (he used to support immigration, but championed proposition 187, denying all benefits to families of illegal immigrants when unpopular and facing reelection. It worked, but also made the Republicans so unpopular that they've only won something like 2 statewide offices here since.). Both governors appointed Judges who knew their place in the system - don't let criminals go no matter how illogical you must be. Consider how extreme Bird and company were on one side, and be even more absurd in the other direction. To this end, the vast majority of people appointed to Judgships came from the DAs office. Those appointees with a defense background tended to be even harsher law and order types than the DAs (talk to most defense lawyers here and most will agree that the former Public Defenders appointed as Judges frequently were the worst PDs before they became Judges, and didn't get much better after they hit the bench).
The result in the last two decades has been dramatic. The interesting characters who make California a fun place to live and work are for the most part gone. People have become Judges only by pandering to the most base political causes, usually mindless law and order (that law and order mentality goes right out the door, though, when the defendants are the sacred class in California politics - law enforcement. In those rare instances, they get justice the way it is actually written in the books, and not the way it is practiced generally for poor minority clients in the courtrooms of the state). Instead of 59 of 60 death sentences overturned, the same number now get upheld, no matter how egregious the errors, how rife with misconduct from the prosecution, how patently incompetent the defense lawyer may have been. Of course, the Federal Courts have begun overturning this legacy of absurd judging in droves, having overturned on the order of a dozen death sentences in the last year or so.
The worst legacy of this period has been the eviceration of California law contorted to ensure death sentences stand up. Therefore, any error, no matter how bad, any rule, no matter how silly, any result, no matter how absurd, stands up in Supreme Court opinions so that the evil of a death sentence being overturned does not happen. The other legacy is what is called harmless error, something that has infected every trial judge in this state.
What is harmless error? Without resorting to legal mumbo jumbo, it means "alright, that was a screw-up, but it didn't affect the game, so don't sweat it, the conviction stands." Imagine a football game where the referee reviews a call, says "bad call, but you know what, the Raiders sucked, are going to lose the game anyways, so why waste our time trying to fix it now, it's too late for them. Anyways, we hate Al Davis and those damn Raider fans, so it's a net gain for society." That, in a nutshell, is harmless error California. While some errors are clearly harmless, one would not consider the bulk of the errors now called harmless to be so harmless if they cropped up in their own trials. Furthermore, the message from the Supreme Court to trial judges has been clear: "here is the rule, you must follow it, since we said it is so. However, if you fail to follow it, don't worry, for the error will be harmless." Since the police and prosecutors will try to end the career of any judge who follows the law in a way that rules against them, which way do you think most of these judges, who are generally ex-prosecutors and frequently ex-cops, will rule?
Since most of the Judges are ex-DAs, who worked closely with cops throughout their careers and depended on them to reach their present positions, they tend to take the side of law enforcement whenever they have to make a choice. While most Judges will do this, not all will. The prosecution has a weapon to make sure they do. This is called 170.6 affidavit (in the code of Civil Procedure), which allows each side to challenge a Judge on a case for no reason at all. Now, each side gets one of these per case. But stop and think about this. The DA's office is generally the only office prosecuting cases, while there are 2 public defender's offices (in many of the big cities in Cal), as well as a multitude of private lawyers who "papering" a Judge can really hurt their business in the future. So, who do you think has the ability to "paper" a Judge into civil?
If you think that the defense can do it well, consider one situation in the main courthouse in a large Californian city. There is one Judge there that both public defender's offices paper regularly, and have been for several years. And yet, he stays there taking private counsel cases, pro pers (people who represent themselves), and overflow cases where other Judges have been papered. If the DA's office papered him, he'd be in civil before he'd had a chance to read up on his civil law (which he'd probably know little about, since he's practiced criminal law most of his life). Yet, papered by the defense, he remains at the main courthouse ready to wreak havoc on any defendant who appears before him, unbothered by the fact that just about every lawyer who knows the first thing about criminal law thinks his abilities fall somewhere below a first year law student's abilities, to say nothing of his fairness.
The message to Judges is clear - your career can be ruined by the police and prosecution, don't mess with them. The higher courts have given them a green light, the other Judges give them a green light, and the people who really control the courts, the prosecution, have given them a green light (in fact, they really hold all of the traffic signs for the judiciary to follow).
Result - California Courts have gone from one of the most respected and cited courts in the nation, to a joke that gets overturned in just about every situation possible by Federal Courts. But, the Federal Courts can only take a very small number of cases, so a very large number of people sit for increasingly long periods of time in prison after having their cases completely bungled by the DAs behind counsel table, and the DAs on the bench, the supposed "check" on the "real" DAs.