Part I discusses autism spectrum disorders, including the diagnosis and characteristics of autism, and whether autism is linked to criminal behavior. Part II examines whether autism should be an affirmative defense to a crime, and concludes that it should not. However, Part II does propose that autism should be an affirmative defense to specific minor crimes. Part III analyzes potential prejudicial demeanor evidence that might occur when autistic defendants testify in their own defense at a trial. This Part argues that evidence of autism should be admitted in a trial to explain to the jury why an autistic individual may exhibit unconventional social reactions while testifying. Part IV explores sentencing of an autistic defendant, and proposes that autism be a mitigating factor for sentencing. This Note concludes by explaining how implementing the propositions in this Note can lead to a greater awareness of autism spectrum disorders within the legal community.