The power of nullification plays an important role in the criminal justice system. ... Because an accused criminal is restricted in the defenses he or she can raise, the law recognizes only certain defenses and justification, and correspondingly, limited evidence. The jury’s power to nullify provides an accommodation between the rigidity of the law and the need to hear and respond to positions that do not fit legal pigeonholes, such as claims of spousal abuse before the battered-spouse syndrome received acceptance. Jury nullification permits the jury to respond to a position that does not have the status of a legally recognized defense. The power to nullify guarantees that the jury is free to speak as the conscience of the community.
It is clear in our criminal justice system that the jury has the power to nullify -- that is, the power to acquit or to convict on reduced charges despite overwhelming evidence against the defendant. ... In a criminal trial, the court cannot direct a verdict of guilty, no matter how strong the evidence. In addition, if the jury acquits, double jeopardy bars the prosecution from appealing the verdict or seeking retrial. Similarly, if the jury convicts the defendant of a less serious offense than the one charged, the prosecution cannot again try the defendant on the more serious charge. This result occurs regardless of whether the jury consciously rejects the law, embraces a merciful attitude, or is simply confused concerning the law or facts. Thus, nullification -- with or without authority, intended or not -- is part of our system.