Some modern criminal statutes contain language such as the provision that the act must be “knowingly and knowingly” or “with unlawful intent” or similar wording. However, this does not refer to ignorance of the laws, but to criminal intentions. The U.S. Supreme Court has made some exceptions to the “ignorance is no excuse” defense. In Lambert v. 1957 in California, the court ruled that the fact that the defendant (Lambert) had not registered as a criminal after moving to Los Angeles was a “completely passive act.” Lambert, who had previously been convicted of forgery, was unaware of an order requiring her to register as a criminal if she was in the city of Los Angeles for more than five days. Because she was not allowed to use ignorance of the law as a defence, she was fined $250 and sentenced to three years of probation. Lambert could have faced up to six months in jail for every day in the city after exceeding the five-day limit. The court quashed the conviction. Justice William Douglas wrote in the court`s majority opinion: “If a person was not aware of the requirement to register and there was no evidence of the likelihood of such knowledge, he cannot be convicted in accordance with due process.” His future behaviour is therefore no different from a law that punishes ignorant offenders than from a law that excuses them. However, punishing ignorant offenders can have an indirect deterrent effect: the more people are punished, the more notorious the crime. However, deterrence through notoriety seems unlikely to have much impact on the commission of the relatively esoteric regulatory crimes to which ignorance is most often claimed, and whatever deterrence is achieved, it must be weighed against their costs of deterring regulated activities.
The maxim ignorantia juris currently in force in the United States arose from this venerable ancestry. A broad and early acceptance of the maxim can be found in many cases. As with the Roman and British versions, the American version of the principle was often articulated in noble terms: every person – with reasonable understanding is supposed to know the law and act according to the rights it confers or upholds – and “there is culpable negligence in him to commit an act. and then to put forward his ignorance of the law as a defence. But after examining other justifications of the doctrine, this argument of ignorance legis seems the most plausible. Holmes` objection to this reasoning is based on a false factual predicate. Ignorance of the law may be punished only if it results in a violation of the law; This coincidence, and not mere ignorance, is punished to the same extent as knowingly and intentionally breaking the law. In any event, if ignorance of the law does not excuse because it is guilty, the judge or jury should consider whether the particular ignorance alleged by a defendant is actually guilty. A final endorsement of ignoranceantia legis, offered by Jerome Hall, deals more with errors of law than with his ignorance. Although Hall found the origin of ignorantia legis in the Roman idea that the law was definitive and knowable, he argued that the defense of doctrine must be based on the inevitable indeterminacy of the law. In England, the maxim has taken on a less lenient occupation. Although it appears that the maxim derives from civil actions under Roman law, English courts have also allowed it to control the outcome of crimes.
Moreover, English common law courts have distinguished between allegations of ignorance or errors of law and errors of fact. Errors of fact were generally considered a defence, while errors of law were generally not considered a defence. An old maxim of the law is ignorantia juris non excusat, or ignorance of the law does not excuse. In other words, it is assumed that the public knows the laws and that a defense of ignorance is generally not allowed. This principle is at the heart of the recent state Supreme Court decision in State v. Miller, ___ N.C. ___, (June 9, 2017). In both cases, the court explains what the law is, but also declares that the defendant is not criminally responsible for the violation of the law. The court therefore theoretically remains the proclaimer; The excuse of an error of law will not affect the legislative function of the courts in practice, unless it interferes with obedience to the declared law. If the excuse out of ignorance of a law did not reduce the deterrent effect of the law, then the excuse of a misconception about the meaning of a law should not have a greater negative effect. With the proliferation of criminal law, no U.S.
citizen can reasonably expect to know all applicable laws. Ignorance of the law may not be an excuse, but for virtually 100% of Americans, ignorance is reality. According to Harvey Silverglate, a respected lawyer and author, the average American can commit three crimes a day without knowing it.  In criminal law, ignorance, while not relieving a defendant of guilt, may be a factor to consider in sentencing, especially if the law is unclear or if the defendant has sought advice from law enforcement or regulatory agencies.