Ignorantia juris non excusat
Ignorantia juris non excusat or ignorantia legis neminem excusat (Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 for "ignorance
Ignorance is a state of being uninformed . The word ignorant is an adjective describing a person in the state of being unaware and is often used as an insult...

 of the law
Law is a system of rules and guidelines which are enforced through social institutions to govern behavior, wherever possible. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus...

 does not excuse" or "ignorance of the law excuses no one") is a legal principle holding that a person who is unaware of a law may not escape liability
Legal liability
Legal liability is the legal bound obligation to pay debts.* In law a person is said to be legally liable when they are financially and legally responsible for something. Legal liability concerns both civil law and criminal law. See Strict liability. Under English law, with the passing of the Theft...

 for violating that law merely because he or she was unaware of its content. In the United States, exceptions to this general rule are found in cases such as Lambert v. California
Lambert v. California
Lambert v. California, 355 U.S. 225 , was a United States Supreme Court case regarding the acceptability of ignorance of the law as an excuse for a crime. The court held that in order to be punished, there must be a probability that the accused party had knowledge of the law before committing the...

(knowledge of city ordinances) and Cheek v. United States
Cheek v. United States
In Cheek v. United States, 498 U.S. 192 , the United States Supreme Court reversed the conviction of John L. Cheek, a tax protester, for willful failure to file tax returns and pay tax...

(willfulness requirement in U.S. federal tax crimes).

European law countries with a tradition of Roman law may also use the expression nemo censetur ignorare legem: nobody is thought to be ignorant of the law.


The rationale of the doctrine is that if ignorance were an excuse, a person charged with criminal offenses or a subject of a civil lawsuit
A lawsuit or "suit in law" is a civil action brought in a court of law in which a plaintiff, a party who claims to have incurred loss as a result of a defendant's actions, demands a legal or equitable remedy. The defendant is required to respond to the plaintiff's complaint...

 would merely claim that he or she is unaware of the law in question to avoid liability, even though the person really does know what the law in question is. Thus, the law imputes
Imputation (law)
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...

 knowledge of all laws to all persons within the jurisdiction
Jurisdiction is the practical authority granted to a formally constituted legal body or to a political leader to deal with and make pronouncements on legal matters and, by implication, to administer justice within a defined area of responsibility...

 no matter how transiently. Even though it would be impossible, even for someone with substantial legal training, to be aware of every law in operation in every aspect of a state's activities, this is the price paid to ensure that willful blindness
Willful blindness
Willful blindness is a term used in law to when an individual seeks to avoid civil or criminal liability for a wrongful act by intentionally putting himself in a position where he will be unaware of facts which would render him liable.For example, in a number of cases,...

 cannot become the basis of exculpation. Thus, it is well settled that persons engaged in any undertakings outside what is common for a normal person, such as running a nuclear power plant
Nuclear power plant
A nuclear power plant is a thermal power station in which the heat source is one or more nuclear reactors. As in a conventional thermal power station the heat is used to generate steam which drives a steam turbine connected to a generator which produces electricity.Nuclear power plants are usually...

, will make themselves aware of the laws necessary to engage in that undertaking. If they do not, they cannot complain if they incur liability.

The doctrine assumes that the law in question has been properly published and distributed, for example, by being printed in a government gazette, made available over the internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...

, or printed in volumes available for sale to the public at affordable prices.

In the criminal law
Criminal law
Criminal law, is the body of law that relates to crime. It might be defined as the body of rules that defines conduct that is not allowed because it is held to threaten, harm or endanger the safety and welfare of people, and that sets out the punishment to be imposed on people who do not obey...

, although ignorance may not clear a defendant of guilt
Guilt is the state of being responsible for the commission of an offense. It is also a cognitive or an emotional experience that occurs when a person realizes or believes—accurately or not—that he or she has violated a moral standard, and bears significant responsibility for that...

, it can be a consideration in sentencing
Sentence (law)
In law, a sentence forms the final explicit act of a judge-ruled process, and also the symbolic principal act connected to his function. The sentence can generally involve a decree of imprisonment, a fine and/or other punishments against a defendant convicted of a crime...

, particularly where the law is unclear or the defendant sought advice from law enforcement or regulatory officials. For example, in one Canadian
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 case, a person was charged with being in possession of gambling
Gambling is the wagering of money or something of material value on an event with an uncertain outcome with the primary intent of winning additional money and/or material goods...

 devices after they had been advised by customs
Customs is an authority or agency in a country responsible for collecting and safeguarding customs duties and for controlling the flow of goods including animals, transports, personal effects and hazardous items in and out of a country...

 officials that it was legal to import such devices into Canada. Although the defendant was convicted, the sentence was an absolute discharge.

In addition, there were, particularly in the days before satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

 communication and cellular phones, persons who could genuinely be ignorant of the law due to distance or isolation. For example, in a case in British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

, a pair of hunters were acquitted of game offenses where the law was changed during the period they were in the wilderness hunting. In reaching this decision, the court refused to follow an early English law
English law
English law is the legal system of England and Wales, and is the basis of common law legal systems used in most Commonwealth countries and the United States except Louisiana...

 case in which a seaman on a clipper
A clipper was a very fast sailing ship of the 19th century that had three or more masts and a square rig. They were generally narrow for their length, could carry limited bulk freight, small by later 19th century standards, and had a large total sail area...

 before the invention of radio
Invention Of Radio
Within the history of radio, several people were involved in the invention of radio and there were many key inventions in what became the modern systems of wireless. Radio development began as "wireless telegraphy"...

 was convicted even though the law had been changed while he was at sea (Bailey (1800) Russ & Ry 1).

An alternate explanation of the origin of the maxim, though not particular relevant to the modern context, can be found with the philosophy of the Greeks and Romans. These were cultures heavily influence by customary legal systems. Within such a system, law is learned as a person participates in the culture and customs of the community. Thus it is unreasonable to believe a person could have avoided learning them. These rules and customs were also interwoven with ethical and religious dialog so that law expresses what is right and good and deviation that which is not. We find that Cicero
Marcus Tullius Cicero , was a Roman philosopher, statesman, lawyer, political theorist, and Roman constitutionalist. He came from a wealthy municipal family of the equestrian order, and is widely considered one of Rome's greatest orators and prose stylists.He introduced the Romans to the chief...

 wrote the following in De re publica
De re publica
De re publica is a dialogue on Roman politics by Cicero, written in six books between 54 and 51 BC. It is written in the format of a Socratic dialogue in which Scipio Africanus Minor takes the role of a wise old man — an obligatory part for the genre...

(On the Republic):

"There is a true law, right reason, agreeable to nature, known to all men, constant and eternal, which calls to duty by its precepts, deters from evil by its prohibition. This law cannot be departed from without guilt. Nor is there one law at Rome and another at Athens, one thing now and another afterward; but the same law, unchanging and eternal, binds all races of man and all times."

Plato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the...

 wrote similarly in Minos
Minos (dialogue)
Minos is one of the dialogues of Plato, featuring Socrates and a Companion. Its authenticity is doubted by W. R. M. Lamb because of its unsatisfying character, though he does consider it a "fairly able and plausible imitation of Plato's early work." Edith Hamilton and Huntington Cairns do not even...


"What’s right is right and what’s wrong is wrong. And isn’t this believed by everyone ... even among the Persians, and always? ... What is fine, no doubt, is everywhere legislated as fine, and what is shameful as shameful; but not the shameful as fine or the fine as shameful."


Presumed knowledge of the law is the principle in jurisprudence
Jurisprudence is the theory and philosophy of law. Scholars of jurisprudence, or legal theorists , hope to obtain a deeper understanding of the nature of law, of legal reasoning, legal systems and of legal institutions...

 that one is bound by a law even if one does not know of it. It has also been defined as the "prohibition of ignorance of the law".

The concept comes from Roman law
Roman law
Roman law is the legal system of ancient Rome, and the legal developments which occurred before the 7th century AD — when the Roman–Byzantine state adopted Greek as the language of government. The development of Roman law comprises more than a thousand years of jurisprudence — from the Twelve...

, and is expressed in the brocard ignorantia legis non excusat.

The essential public character of a law requires that the law must apply to anyone in the jurisdiction
Jurisdiction is the practical authority granted to a formally constituted legal body or to a political leader to deal with and make pronouncements on legal matters and, by implication, to administer justice within a defined area of responsibility...

 where the law applies. Thus, no one can justify his conduct on the grounds that he was not aware of the law.

Generally, a convention exists (by some called "the essential preliminary rule") by which the laws are issued and rendered accessibile by methods, authors and means that are simple and well known: the law is readable in certain places (some systems prescribe that a collection of the laws is copied in every local city council), is made by certain authorities (usually sovereign, government, parliament, and derivative bodies), and enters into effect in certain ways (many systems for instance prescribe a certain number of days - often 15 - after issue). This is commonly intended as a constitutional
Constitutional law
Constitutional law is the body of law which defines the relationship of different entities within a state, namely, the executive, the legislature and the judiciary....

 regulation, and in fact many constitution
A constitution is a set of fundamental principles or established precedents according to which a state or other organization is governed. These rules together make up, i.e. constitute, what the entity is...

s or statute
A statute is a formal written enactment of a legislative authority that governs a state, city, or county. Typically, statutes command or prohibit something, or declare policy. The word is often used to distinguish law made by legislative bodies from case law, decided by courts, and regulations...

s exactly describe the correct procedures.

However, some recent interpretations weaken this concept. Particularly in civil law
Civil law (legal system)
Civil law is a legal system inspired by Roman law and whose primary feature is that laws are codified into collections, as compared to common law systems that gives great precedential weight to common law on the principle that it is unfair to treat similar facts differently on different...

, regard can be had to the difficulty of being informed of the existence of a law considering the lifestyle of the average citizen. On the penal side, the quality of the knowledge of the law can affect the evaluation of the animus nocendi
Animus nocendi
In jurisprudence, animus nocendi is the subjective state of mind of the author of a crime, with reference to the exact knowledge of illegal content of his behaviour, and of its possible consequences....

 or the mens rea
Mens rea
Mens rea is Latin for "guilty mind". In criminal law, it is viewed as one of the necessary elements of a crime. The standard common law test of criminal liability is usually expressed in the Latin phrase, actus non facit reum nisi mens sit rea, which means "the act does not make a person guilty...

, in that certain subjective conditions can weaken personal responsibility.

The theme was widely discussed, also for political reasons, at the time of the Enlightenment and in the 18th century, given the heavy proportion of illiterate citizens in European countries (who would have some difficulties being aware of all the laws in a country). It was then argued that both the presumed knowledge and the heavily increasing corpus of national legislation were working in favour of lawyers rather than citizens.

In recent times, some authors have considered this concept as an extension of (or at least as analogous to) the other ancient concept (typical of criminal law
Criminal law
Criminal law, is the body of law that relates to crime. It might be defined as the body of rules that defines conduct that is not allowed because it is held to threaten, harm or endanger the safety and welfare of people, and that sets out the punishment to be imposed on people who do not obey...

) that no one can be punished under a law that was issued after the action was committed (non-retroactivity of the law. See ex post facto). This interpretation is however disputed, given that the matter would hierarchically more properly refer to a constitutional doctrine rather than to a civil or penal one.

Some modern criminal statutes contain language such as stipulating that the act must be done "knowingly and wittingly" or "with unlawful intent," or some similar language.

Into law

This principle is also stated into law:
  • Canada: Criminal Code (RSC 1985, c. C-46)
    Criminal Code of Canada
    The Criminal Code or Code criminel is a law that codifies most criminal offences and procedures in Canada. Its official long title is "An Act respecting the criminal law"...

    , section 19
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.