In California, juries are told that they may not convict unless they are convinced beyond all reasonable doubt that the defendant is guilty.
While this sounds simple, it's very difficult for a jury to understand or to properly use this standard. When a jury is asked to decide on a defendant's guilt, they see it as a choice between two sides, between guilt and innocence. The prosecutor wants a conviction and the defendant wants to go home.
We make decisions every day; we regularly have to choose between two options, and our natural tendency is to simply choose the better of the two options.
When it comes to jury duty in a criminal case, when a juror is asked to decide between guilt vs. innocence, a juror is asked to make a choice by a different standard, the standard of proof beyond a reasonable doubt. Choosing the better of two options is not what a juror is called upon to do in this context.
Yes, frequently the prosecutor's theory of guilt is the better option when compared to the defendant's theory of innocence. A defendant's case often relies on a theory that is not supported by witnesses who are regarded as reliable as the police officers who testified for the prosecution. The government uses well-funded laboratories, police officers who testify frequently, paid informants, and other advantageous tools while a defendant, if he cannot afford to pay experts, must go to the court and beg for money to provide him with an adequate defense. He must send his investigator to interview witnesses who, after giving statements to police, are told they don't have to talk to anyone else.
Many times a defendant cannot testify in his own defense for fear that his past will be used against him. Even if he has no prior convictions, the prosecutor will call him a liar and will tell the jury that his testimony is motivated only by a desire to avoid the consequences of his evil actions. If he chooses not to testify, the jury will wonder why. They'll ask themselves "if he's really innocent, why doesn't he just testify and proclaim his innocence? That's what I'd do!" Of course the court will tell the jury that the defendant's silence should not be considered, but most jurors cannot follow such an instruction. They agree during the jury selection process that they can presume innocence and refrain from holding the defendant's silence against him, but they'll always wonder about him and why he won't talk. They'll assume guilt if he's silent, and suspect deception if he testifies.
Add to this the fact that most jurors want to believe the prosecutor and his police witnesses. If innocent men can be charged, what is there to protect the jurors themselves from being arrested? Deep down inside they know that bad things happen even to good people, that innocent men as well as the guilty are charged by prosecutors who want to win their cases even at the expense of their ethical duty to seek justice. But no juror wants to believe what they know inside. A juror doesn't want to acknowledge that he or she could ever be charged, or that the government could ever be so mistaken as to accuse an innocent man of a crime. Finding a defendant not guilty would shatter the juror's sense of comfort and immunity from trouble.
When a jury believes that someone probably is guilty, that is, he is more likely guilty than innocent, the jury feels obligated to find guilt by a sense of duty to the community and a desire to live safe from crime.
Juries naturally tend to want to choose the better of two options. The prosecutor's advantages generally make guilt the "better" option, the more likely true option. Juries feel morally obligated to punish a criminal, and are likely to go with a finding of guilt based on a "probably" standard.
What, then, of reasonable doubt? It is a standard to which jurors in America often pay lip service. They believe that it means to be really sure that the option they chose, usually guilt, is the better of the two options. In so doing they diminish the protections for us all. They make it easier for a government to deprive its citizens of their liberty, right or wrong.
The value of liberty was considered by our founders to be so high that people who are probably guilty are entitled to keep it. Think about that for a minute - the founding fathers whose wisdom secured for us our rights to privacy, freedom of speech and religion, and gave us a say in the selection of our leaders felt it more important to protect the rare but real innocent man who stands accused, even if this standard means that guilty people sometimes go free. A guilty person occasionally going free is the price of freedom to the falsely accused, a price that all who value their freedom should gladly pay. By using the reasonable doubt standard, the founders sought to ensure that the government would diligently and justly go after the truly guilty, that they would do so with good evidence only, and that non-government people, jurors, would have the final say on whether the government's case was good enough to deprive a person of his liberty.
When someone swears to follow the law and to justly judge a case as a juror, and to hold the government to the reasonable doubt standard, he or she takes on an obligation to the whole of American civilization. For such is the nature of the juror's duty - to hold in check a government that is otherwise empowered to indiscriminately deprive its people of their liberty. If one cannot do this, one should admit as much and decline to serve as a juror.
When a juror claims that he or she can follow the law but instead follows his or her tendency to revert to a "which theory is better?" standard, when he or she gives in to the temptation to convict because the defendant "probably" did it, the juror helps erode their own freedom and that of their children and grandchildren. The juror takes a sledgehammer to the foundation of our free society.
One of the highest priorities of any criminal defense attorney should be to ensure that his client is tried before a jury who is willing and able to follow the law. To this end a lawyer should remind the jury of the burden as often as he can, and he should especially argue the case to the proper standard. Time and again I see attorneys argue that the defense's theory is better than the prosecutor's, that the defendant is more likely innocent than guilty. Even if this is true, arguing in this manner is conceding to the jury that the case should be tried by the wrong standard.
We should never give - even a little - on the burden of proof. The prosecutor must prove our clients guilty beyond a reasonable doubt or see him out the door and on his way to a life of freedom. We should insist on jurors who will judge the case by the proper standard. By the standard of reasonable doubt.