Is jury nullification proper under some circumstances?

The principle of jury nullification allows a trial jury to rule in contradiction to facts about the case. In a civil trial, nullification occurs when the jury finds the defendant not liable even when jurors may believe the defendant is liable. In criminal cases, nullification occurs when the jury finds the defendant not guilty even when jurors may believe the defendant is guilty, but they do not believe he or she should be punished for the illegal act.
Jury nullification comes into practice when members of the jury disagree with the law or how the law is being applied in the particular case. Historically, jury nullification was used in the United States when jurors refused to convict those accused of violating the Fugitive Slave Act. Jury nullification also occurred in the American colonial period when juries refused to convict a defendant under English law.  
A modern example is the case of William Lynch who was charged with assault. The jurors did not deny he had committed assault, as Lynch openly confessed his guilt. However, the assault occurred in an emotionally charged situation when Lynch was confronting the victim, a priest who had sexually abused him as a child. In this situation, the jurors invoked jury nullification in order to not convict Lynch.
Thus, jurors are granted discretion through jury nullification to consider the circumstances of individual cases, exercise their consciences and common sense, and temper law with mercy.