Posted on 2/12/18

Say the police arrest someone for murder. At trial, the prosecution provides compelling evidence that the defendant committed the crime. The defense team calls the defendant to the stand. There, the defendant tells the jury about his miserable upbringing and how he did not know that it is illegal to kill someone. Suppose that his testimony is compelling and believable. Nonetheless, the jury returns with a guilty verdict, sending the defendant to Texas’s death row.

Mistake of law isalmost never a defense in Texas. Even if a defendant reasonably did not know the law and even if the defendant is illiterate an unable to read the law, mistake of law is not a defense. This article discusses the two theories why mistake of law is not a defense.


The first theory is that a legitimate mistake of law defense will be chaotic. Imagine every defendant claiming that he or she does not know of a law. It would be highly difficult for a prosecutor to prove that a defendant did, in fact, know the law. Such a defense would subsume the whole criminal justice system. It goes to the adage that ignorance of the law is not a defense or the adage that every person is presumed to know the law.

The argument against this theory is that and defendant who claims mistake of law will be an affirmative defense. That is to say, a defendant claiming mistake of law must prove that he or she was really ignorant of the law. It would be a high bar to prove such ignorance.

Another theory given is that banning a mistake of law defense acts as a deterrent to crime. That is to say, if mistake of law is not a defense then people will be compelled to know and understand the basics of the law. If people do not have this incentive, people will not look to know the law or negligently ignore opportunities to learn about what is legal and what is not. Such a society may be chaotic, not just for a specific criminal act.

This leads to questions about unjust convictions. According to this theory, mistake of law, by itself, is a valid defense; society does not accept it as a defense because it has too much collateral damage, i.e. people maintaining and making sure that they are ignorant of the law, which in turn leads to more law breaking. As a result, people who legitimately did not know about the law, meaning that they are not merely people who refused to do any research or were particularly negligent about gaining knowledge of the law, and cannot use this defense, will then be punished for breaking the law. This will result in injustice. People will face criminal restitution, go to prison, and sit on death row despite legitimately not knowing about the law.

Academics aside, the law in Texas is that mistake of law is almost never a defense to a crime.

Accused of a crime? You need a lawyer who is a strong advocate. Contact the law office Christopher Abel.

(image courtesy of Claire Anderson)

Flower Mound Office

Phone: 972.584.7837

Denton Office