Stalking occurs when one person follows or harasses another person for no legitimate purpose and does so with the intent of causing them fear or emotional distress. From this definition, we can see how purpose could be a defense.
If a person accused of stalking can show a legitimate purpose for his or her actions, this can be the basis of a defense. The accused could claim, for example, that he went to the same stores the alleged victim did simply so he could go shopping. He could claim that he followed his ex-wife to ensure that she was complying with court orders concerning their children. In such instances, the accused could use purpose as a defense by showing that his conduct had a legitimate purpose.