The M'Naghten rule is any variant of the 1840s jury instruction in a criminal case when there is a defence of insanity:
that every man is to be presumed to be sane, and ... that to establish a defence on the ground of insanity, it must be clearly proved that, at the time of the committing of the act, the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing; or if he did know it, that he did not know he was doing what was wrong.
Mens rea is the mental element of a person's intention to commit a crime; or knowledge that one's action or lack of action would cause a crime to be committed. It is a necessary element of many crimes.
Beyond a reasonable doubt is a legal standard of proof required to validate a criminal conviction in most adversarial legal systems. It is a higher standard of proof than the balance of probabilities and is usually therefore reserved for criminal matters where what is at stake is considered more serious and therefore deserving of a higher threshold.
An attempt to commit a crime occurs if a criminal has an intent to commit a crime and takes a substantial step toward completing the crime, but for reasons not intended by the criminal, the final resulting crime does not occur. Attempt to commit a particular crime is a crime, usually considered to be of the same or lesser gravity as the particular crime attempted. Attempt is a type of inchoate crime, a crime that is not fully developed. The crime of attempt has two elements, intent and some conduct toward completion of the crime.
Willful blindness is a term used in law to describe a situation in which a person seeks to avoid civil or criminal liability for a wrongful act by intentionally keeping themselves unaware of facts that would render them liable or implicated. In United States v. Jewell, the court held that proof of willful ignorance satisfied the requirement of knowledge as to criminal possession and importation of drugs.
An accessory is a person who assists in, but does not actually participate in, the commission of a crime. The distinction between an accessory and a principal is a question of fact and degree:
A mistake of fact may sometimes mean that, while a person has committed the physical element of an offence, because they were labouring under a mistake of fact, they never formed the mental element. This is unlike a mistake of law, which is not usually a defense; law enforcement may or may not take for granted that individuals know what the law is.
In law, the principle of imputation or attribution underpins the concept that ignorantia juris non excusat—ignorance of the law does not excuse. All laws are published and available for study in all developed states. The content of the law is imputed to all persons who are within the jurisdiction, no matter how transiently.
Cheek v. United States, 498 U.S. 192 (1991), was a United States Supreme Court case in which the Court reversed the conviction of John L. Cheek, a tax protester, for willful failure to file tax returns and tax evasion. The Court held that an actual good-faith belief that one is not violating the tax law, based on a misunderstanding caused by the complexity of the tax law, negates willfulness, even if that belief is irrational or unreasonable. The Court also ruled that an actual belief that the tax law is invalid or unconstitutional is not a good faith belief based on a misunderstanding caused by the complexity of the tax law, and is not a defense.
The criminal law of Canada is under the exclusive legislative jurisdiction of the Parliament of Canada. The power to enact criminal law is derived from section 91(27) of the Constitution Act, 1867. Most criminal laws have been codified in the Criminal Code, as well as the Controlled Drugs and Substances Act, Youth Criminal Justice Act and several other peripheral statutes.
In English criminal law, intention is one of the types of mens rea that, when accompanied by an actus reus, constitutes a crime.
The Model Penal Code (MPC) is a model act designed to stimulate and assist U.S. state legislatures to update and standardize the penal law of the United States of America. The MPC was a project of the American Law Institute (ALI), and was published in 1962 after a ten-year drafting period. The chief reporter on the project was Herbert Wechsler, and contributors included Sanford Kadish and numerous other noted criminal law scholars, prosecutors, and defense lawyers.
Lambert v. California, 355 U.S. 225 (1957), was a United States Supreme Court case regarding the defense of ignorance of the law when there is no legal notice. The court held that, when one is required to register one's presence, failure to register may only be punished when there is a probability that the accused party had knowledge of the law before committing the crime of failing to register.
Ignorantia juris non excusat or ignorantia legis neminem excusat is a legal principle holding that a person who is unaware of a law may not escape liability for violating that law merely by being unaware of its content.
Berry v. Superior Court, 256 Cal. Rptr. 344 (1989), is an unofficially reported California Court of Appeal case. The case is relevant to the legal topic of criminal homicide and liability for unintentional killings.
Aiding and abetting is a legal doctrine related to the guilt of someone who aids or abets another person in the commission of a crime. It exists in a number of different countries and generally allows a court to pronounce someone guilty for aiding and abetting in a crime even if they are not the principal offender. The words aiding, abetting and accessory are closely used but have differences. While aiding means providing support or assistance to someone, committing a crime in exchange of a commission or compensation, abetting means encouraging someone else to commit a crime. Accessory is someone who in fact assists "commission of a crime committed primarily by someone else".
McFadden v. United States, 576 U.S. 186 (2015), was a United States Supreme Court case in which the Court held that section 841 of the Controlled Substances Act requires the government to prove that to be in criminal violation, a defendant must be aware that an analogue defined by the Controlled Substance Analogue Enforcement Act with which he was dealing was a controlled substance.
The ostrich instruction is a jury instruction that the requirement of knowledge to establish a guilty mind, is satisfied by deliberate ignorance - deliberate avoidance of knowledge. It arose from the case of United States v. Jewell.
United States v. Giovanetti, 919 F.2d 1223, is a criminal case that interpreted the jury instruction known as the ostrich instruction, that willful ignorance counted as knowledge where required for a guilty mind in complicity to commit a crime. The court held that willful ignorance required a positive act to avoid knowledge, otherwise it reduces the mens rea requirement of proving "knowledge" to merely proving "negligence".
Two main questions arise in the law surrounding driving after having ingested cannabis: (1) whether cannabis actually impairs driving ability, and (2) whether the common practice of testing for THC is a reliable means to measure impairment. On the first question, studies are mixed. Several recent, extensive studies–including one conducted by the National Highway Traffic Safety Administration and one conducted by the American Automobile Association (AAA)–show that drivers with detectable THC in their blood are no more likely to cause car crashes than drivers with no amount of THC in their blood. Others show that cannabis can impair certain abilities important to safe driving –but no studies have been able to show that this increases the actual risk of crashing, or that drivers with THC in their blood cause a disproportionate number of crashes. On the second question, the studies that have been conducted so far have consistently found that THC blood levels and degree of impairment are not closely related. No known relationship between blood levels of THC and increased relative crash risk, or THC blood levels and level of driving impairment, has been shown by single-crash or classic-control studies. Thus, even though it is possible that cannabis impairs driving ability to some extent, there are currently no reliable means to test or measure whether a driver was actually impaired.
