( CNN ) -- What is it with juries in high-profile cases in Southern California ? Over the years , they 've become a national joke . But no one is laughing . Instead , with each travesty of justice and every acquittal that should have been a conviction , you 're left wondering just what trial these 12 folks were watching and questioning whether we should have higher standards for who sits on a jury . Sometimes , the juries in local and state courts get it wrong , and the Justice Department must step in and make it right . Think back to the acquittal in April 1992 of four Los Angeles police officers who , one year earlier , savagely beat motorist Rodney King . They walked out of a courtroom in Simi Valley , California , as free men -- sparking days of rioting , looting and violence . At the time , the conventional thinking on newspaper editorial pages and on talk radio was the jurors in that largely white suburb of Los Angeles , which was itself home to many active-duty and retired police officers , saw the police force as their line of defense against undesirables like King . So naturally , the argument went , they would cut them some slack . The officers were tried again , and convicted in federal court of violating King 's civil rights . Justice was finally served . Here we go again . There has n't been much civil unrest over what happened to Kelly Thomas , the homeless and mentally ill man who -- on July 5 , 2011 -- was beaten to death by a swarm of police officers in Fullerton , California . But now that the verdict is in , literally , on the two former officers who were charged in his death , there is plenty of outrage on talk radio , online and in other public forums . Another 12 people who swore an oath to consider the evidence and the law and make sure that justice is served appear to have gotten it terribly wrong . This week , that jury in Santa Ana , California -- a city about 30 miles southeast of Los Angeles -- produced a wave of gasps in the courtroom when it announced that it had found Manuel Ramos , who had been charged with second-degree murder and involuntary manslaughter , and Jay Cicinelli , who was charged with involuntary manslaughter and excessive use of force , not guilty on all counts . What ? The beating was caught on a surveillance tape . When you watch those 33 minutes of footage , assuming you can stomach the experience , it 's hard to believe that anyone could declare the perpetrators `` not guilty . '' The surveillance camera footage shows Thomas being beaten and stunned with a Taser by police until he was unrecognizable and unconscious . You see a defenseless and compliant young man screaming in pain , saying he 's sorry and pleading for help from his father . His words will haunt you , `` Daddy , help ! They 're killing me ! '' According to prosecutors , the young man suffered brain injuries , facial fractures , broken ribs and extensive bruises and abrasions . He wound up lying in a pool of blood . He died five days later . This was not a by-the-book case of police officers using all necessary force to subdue a suspect who was resisting arrest -- a suspect , by the way , who had committed no crime . This was not , as Ramos ' attorney claimed , a case of police offices simply `` doing their job '' with `` no malice in their heart . '' Check the video . Early on in the confrontation , Ramos appears to tell the young man who is sitting on the ground : `` You see my fists ? They 're getting ready to f -- - you up ! '' Another officer is heard telling a comrade : `` We ran out of options so I got to the end of my Taser and I ... smashed his face to hell . '' There is the malice . This was abuse of power and an instance of bullying behind a badge . It happens more than we 'd like to think in America . But this time , it went too far . And a man died , and a family was shattered . Yet , the jury somehow missed all this ? How does this happen ? In Los Angeles , people are saying that the mentally ill are the new Rodney King . In the same way that the jury in Simi Valley was inclined to back the officers who it saw as protecting them from people like King , now the jury in Santa Ana is backing the officers who it counts on to prod people like Thomas to move along , leave the streets , and get out of sight . It 's a plausible explanation . Human beings are n't perfect , and sometimes those who sit on juries are plagued by their own prejudices -- in this case , against those who behave in erratic ways which we do n't understand . This much we can understand : Cops are supposed to protect the weak , not prey on them . Just like they 're supposed to protect all of us . The tragedy of Kelly Thomas raises a question : When police officers lose control and go from public servants to violent bullies , who will protect us from them ? In this case , there is only one answer and one place left that can right this wrong : The Justice Department . The opinions expressed in this commentary are solely those of Ruben Navarrette .
Ruben Martinez : Too many high - profile cases in California produce lack of justice . He says jury acquitted two ex - inmates in malicious beating death captured on video . He says case showed abuse of power , bullying behind badge ; happens too often in U.S. prisons : Only one place left that can right this wrong : The Justice Department .