Some lawyers, now mostly unsuccessfully (but more successfully in the past), have argued the following to constitute an appropriate jury instruction: "Ladies & Gentlemen, You have heard character testimony introduced by the defendant. I charge you that having heard all of the evidence, if you have a reasonable doubt on the basis of the character testimony standing alone, meaning in and of itself, you must acquit the defendant."
To be sure, the jury will be correctly told that a "reasonable doubt" is a "doubt based upon a (common sense) reason." That reason, the defendant's attorney will also argue, might be the improbability that the defendant could have committed the crime, given his incredible reputation for honesty and integrity.
But is that the law as it exists today?
Mother Teresa of Calcutta was the iconic figure of her day, enjoying -- and by most accounts, deserving -- a reputation of unimpeachable character. Even aside from her reputation for honesty and integrity, her good works for the poor were extraordinary, as most everyone acknowledges her to have been one of the most "hard-core" philanthropic persons imaginable. Although not yet canonized, Mother Teresa was the closest thing to a living saint (although -- unsurprisingly, given his reputation as a contrarian -- the late Christopher Hitchens complained in his clergy-phobic rant "The Missionary Position" that Mother Teresa was no friend of the poor, only a "friend of poverty").
But crazy things can happen. Suppose, during her lifetime, that Mother Teresa were charged with bank robbery. And assume the eyewitnesses to it were none other than the pope, Nelson Mandela and former Watergate prosecutor Archibald Cox -- witnesses of the utmost integrity. They become unshakeable prosecution witnesses at trial, and all that can save Mother Teresa is her almost universally sterling reputation for integrity and good deeds. Thousands, maybe even millions, of people who don't know her personally (which they are not required to, under the applicable rule of evidence) would willingly testify on her behalf, although the judge would be well within trial management discretion to limit the number of character witnesses who would testify, lest they prove unfairly cumulative. Still, witness after witness would make the alleged commission of robbery by Mother Teresa seem virtually impossible to any jury, and as a result, the jury might very well acquit her.
But let's suppose her trial were, for example, before Judge Jed S. Rakoff of the U.S. District Court for the Southern District of New York. In presiding recently over the noteworthy insider trading trial of Rajat Gupta, whose trial attorneys wanted to trumpet Gupta's heralded reputation for philanthropy, Rakoff essentially proclaimed what he would do with such testimony even if Mother Teresa (Rakoff was clearly seeking the reputed epitome of virtue) were instead before him as a defendant: "If Mother Teresa were charged with bank robbery, the jury would still have to determine whether or not she committed a bank robbery." In light of Hitchens' verbal assault on Mother Teresa, Rakoff might instead have chosen as his example Abraham Lincoln or some other such seemingly peerless figure -- but let's stick here with Mother Teresa.
Given the Gupta prosecutor's stated intention not to refer to Gupta's alleged "greed" at trial -- an indication by the prosecutor that charity was not truly an issue in the case -- the philanthropic side of defendant Gupta's life was simply not laid bare before the jury. Would-be Mother Teresa-like "bank robbers": Watch out! Under Rakoff's tersely stated conception, character testimony (which will obviously be raised in Gupta's appeal, although the judge's analysis seems to comport with Second Circuit case law) is not technically a wild card that, "standing alone," can serve as a knockout counterpunch to strong evidence of guilt.
Put differently, a jury can't find reasonable doubt even if it hears overwhelming evidence that the defendant has the singularly best reputation in the world -- a reputation which would make it virtually impossible for a juror to believe that he committed the crime. A "standing alone" jury charge -- under which a jury could basically grant absolution for an individual's aberrant act(s) of criminal wrongdoing, given a lifetime of reputed "clean living," as articulated in poetic witness encomia -- is largely out of favor in the courts. And well it should be. After all, so many defendants (and white-collar defendants in particular) can easily dress up a trial defense in the pure white linen of charitable and communal acts over the trajectory of their lives so as to accord them what might constitute a "get-out-of-conviction-free" card.
As discussed further below, character or reputation testimony is not technically a "wild card." Still, lawyers who proffer it recognize its definite potential to cause juries to nullify damning evidence. Where jurors become sufficiently wowed by a defendant's reputed trait for integrity, they may be moved to discard, or at least subordinate, the substantive evidence of the crime itself. As a result, a jury's decision to simply disregard even the most powerful evidence of guilt, perhaps due to the defendant's likeability or favorable reputation, allows character testimony to serve as a "back door" basis on which to nullify evidence. The risk is that the fears to which Judge Rakoff alluded in discussing potential trial testimony in Gupta could become reality.
What exactly may character/reputation witnesses testify to? And how are jurors charged to deal with such testimony? Specifically, three modes of such not-really-substantive-evidence are allowed by Rule 405 of the Federal Rules of Evidence. No. 1: A witness can testify to the defendant's reputation ("I have spoken to any number of people with knowledge of the defendant who say she is known for being law-abiding and for her fine reputation for honesty [or some other character trait if that trait is admissible in the context of the particular criminal charge].") No. 2: A witness can testify that he knows the defendant and has a particular opinion of his character ("I have known the defendant for many years and my personal opinion is that he is an honest, or law-abiding, person.") No. 3: Where a person's character or character trait is actually an element of the charge, such as the character trait of "honesty" for use in defending against a perjury charge (or, indeed, an element of the gravamen of a civil claim), the defendant's character may be proven by relevant specific instances of the person's conduct ("While the defendant is charged with falsely certifying corporate documents, I was familiar with the contents of many corporate documents he executed in which he always gave truthful certifications, even though truthfulness in those instances was not always good for him individually.")