Sources of Criminal Law

Sources of Criminal Law

Criminal law does not exist simply because society considers certain conduct wrong. A person can be punished for a crime only when a recognized source of law gives the state legal authority to define the conduct as criminal and impose a lawful punishment.

Understanding the sources of criminal law is therefore essential to understanding criminal responsibility itself.

Where does a criminal offense come from?

Who has the authority to create it?

Can a court create a new crime?

Can a prosecutor decide that conduct is criminal?

Can a legislature make previously lawful conduct a crime?

What happens when federal and state criminal laws overlap?

And what role do constitutions, administrative regulations, judicial decisions, and international law play?

These questions are not merely theoretical. They determine whether a criminal prohibition is legally valid and whether the government has lawful authority to punish a particular person.

The Cornell Legal Information Institute’s Wex materials on criminal law provide a useful starting point for understanding criminal law as the body of law governing crimes and their punishment.

The central principle is straightforward:

Criminal liability must have a legal foundation.

That principle lies at the heart of the rule of law.

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1. What Does “Source of Criminal Law” Mean?

A source of criminal law is a recognized legal authority from which criminal rules derive their validity.

In the United States, the principal source of modern criminal law is legislation. Federal criminal offenses are created by Congress, while state criminal offenses are primarily created by state legislatures.

But legislation is not the only legal authority relevant to criminal law.

The broader legal framework may also involve:

• the Constitution;
• judicial decisions;
• administrative regulations;
• the common law;
• local ordinances;
• treaties and international law;
• and constitutional principles governing the validity and interpretation of criminal statutes.

The precise importance of each source depends upon the jurisdiction.

This distinction is critical because criminal law is not organized identically throughout the world.

A legal system based heavily on statutes operates differently from a traditional common-law system in which judicial decisions historically played a greater role in defining criminal offenses.

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2. Legislation: The Principal Source of Modern Criminal Law

In contemporary American criminal law, statutes are the principal source of criminal offenses.

A legislature may enact a statute declaring that particular conduct constitutes a crime and specifying the applicable punishment.

For example, a legislature may enact laws criminalizing:

• murder;
• assault;
• theft;
• fraud;
• burglary;
• bribery;
• drug trafficking;
• computer crimes;
• and numerous other forms of conduct.

A criminal statute generally identifies the prohibited conduct and establishes the legal consequences of violating the prohibition.

This legislative function is fundamental because criminal punishment is a serious exercise of governmental power.

If the government is going to imprison or otherwise punish a person, the legal system ordinarily requires a clear legal basis for doing so.

Legislation therefore provides both criminal prohibitions and democratic authorization for their enforcement.

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3. Federal and State Criminal Legislation

The United States has a federal system of government.

This means that criminal law can arise from both federal legislation and state legislation.

Congress has authority to create federal criminal offenses within the scope of its constitutional powers.

State legislatures possess much broader general authority over criminal law within their respective jurisdictions, subject to their state constitutions and the U.S. Constitution.

Consequently, the same general type of conduct can sometimes implicate both federal and state law.

For example, fraud, drug trafficking, firearms offenses, financial crimes, and organized criminal activity may be addressed by federal statutes as well as state criminal laws.

The existence of federal and state criminal laws does not mean that every crime is automatically a federal offense.

Federal criminal jurisdiction must have a constitutional and statutory foundation.

This makes federalism an important part of understanding the sources of American criminal law.

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4. The United States Constitution

The Constitution is not simply another source of criminal offenses.

Its role is fundamentally different.

The Constitution establishes the structure and limits of governmental power and imposes important restrictions on criminal legislation and criminal punishment.

In other words:

The Constitution can limit what government may criminalize and how it may punish, even when a legislature has enacted a criminal statute.

Constitutional provisions relevant to criminal law include protections involving:

• due process;
• equal protection;
• unreasonable searches and seizures;
• self-incrimination;
• double jeopardy;
• confrontation;
• jury trials;
• excessive bail;
• excessive fines;
• and cruel and unusual punishment.

The Constitution therefore functions as a higher-law constraint on criminal legislation.

A statute does not become valid merely because a legislature enacted it.

It must also comply with the Constitution.

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5. Constitutional Criminal Procedure vs. Substantive Criminal Law

The Constitution affects both substantive criminal law and criminal procedure, but these should be distinguished.

Substantive criminal law asks:

What conduct may constitutionally be defined as a crime?

Criminal procedure asks:

What constitutional rules govern the government’s investigation and prosecution of that crime?

For example, constitutional protections can affect whether a criminal statute is impermissibly vague or retroactive.

Other constitutional protections govern searches, interrogation, counsel, trials, and evidence.

This distinction will become increasingly important as we move through the Criminal Law and Criminal Procedure sections.

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6. The Principle of Legality

The relationship between criminal law and its sources is governed by one of the most fundamental principles in criminal jurisprudence: legality.

The principle is traditionally expressed through the Latin maxim:

Nullum crimen sine lege.

Literally, this means:

No crime without law.

A related principle is:

Nulla poena sine lege.

No punishment without law.

Together, these principles express the idea that people should not be punished for conduct that was not criminally prohibited under applicable law.

Legality serves several purposes.

It provides fair notice.

It limits arbitrary government action.

It prevents retroactive criminalization.

It promotes consistency.

And it reinforces the rule of law.

A person should be able to know, before engaging in conduct, whether the law treats that conduct as criminal.

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7. Why Legislatures Create Criminal Laws

Legislatures criminalize conduct for many reasons.

They may seek to protect:

• human life;
• physical safety;
• property;
• economic systems;
• public institutions;
• national security;
• vulnerable populations;
• public health;
• or the administration of justice.

But criminalization involves more than identifying harmful conduct.

The legislature must also determine whether criminal punishment is an appropriate response.

Not every undesirable behavior needs to become a crime.

Some conduct may be better regulated through:

• civil liability;
• administrative sanctions;
• licensing systems;
• taxation;
• professional discipline;
• or other regulatory mechanisms.

The decision to criminalize therefore involves both legal and policy judgments.

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8. Common Law as a Historical Source of Criminal Law

The role of the common law requires special attention.

Historically, English common law played an enormous role in defining criminal offenses.

Before modern legislatures enacted comprehensive criminal codes, many criminal offenses were developed through judicial decisions and accumulated legal precedent.

Judges interpreted earlier decisions and gradually established legal principles concerning offenses such as:

• murder;
• manslaughter;
• larceny;
• burglary;
• robbery;
• and other common-law crimes.

This historical development had a profound influence on American law.

Many concepts in modern American criminal law—including distinctions involving mens rea, homicide, theft, attempt, conspiracy, and accomplice liability—have roots in common-law jurisprudence.

But the historical importance of common law does not mean that courts today can freely invent criminal offenses.

That distinction is essential.

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9. Common-Law Crimes and Modern American Criminal Law

The modern American approach generally places much greater emphasis on legislative criminal statutes than the traditional English common-law system did.

At the federal level, there is no general federal common-law power to create criminal offenses.

Federal crimes must generally rest upon constitutional and statutory authority.

State systems vary, and historical common-law doctrines have sometimes continued to influence state criminal law, but statutes and constitutional provisions now dominate modern criminal-law analysis.

This development reflects a broader movement toward the principle that criminal offenses should be clearly defined by democratically enacted law.

The shift from judge-developed offenses toward statutory criminal codes is closely connected to legality and separation of powers.

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10. Judicial Decisions as a Source of Criminal Law

Judicial decisions remain extremely important even though courts ordinarily do not possess unlimited authority to create crimes.

Courts interpret criminal statutes.

They determine what statutory language means.

They resolve disputes about ambiguous terms.

They establish how legal standards apply to particular facts.

They determine whether statutes comply with constitutional requirements.

And they develop precedent that guides later courts.

Judicial decisions can therefore have enormous practical influence over criminal law.

For example, a statute may prohibit conduct performed “knowingly.”

A court may have to determine what knowledge means in that particular statutory context.

Another statute may prohibit conduct performed “recklessly.”

A court may need to determine what level of awareness and disregard of risk satisfies that requirement.

The legislature creates the offense.

The judiciary interprets the legal rule and applies it to cases.

This division reflects the constitutional principle of separation of powers.

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11. Statutory Interpretation in Criminal Cases

Criminal statutes frequently contain terms that require interpretation.

Words such as:

• knowingly;
• intentionally;
• willfully;
• recklessly;
• substantially;
• materially;
• possession;
• serious bodily injury;
• and reasonable belief

may require judicial clarification.

Courts therefore play a central role in determining how criminal statutes operate.

But criminal interpretation raises a special concern.

Because criminal punishment can deprive a person of liberty, courts must be particularly careful not to expand criminal statutes beyond their lawful meaning.

This is one reason the rule of lenity has historically played an important role in American criminal law.

When a criminal statute remains genuinely ambiguous after ordinary interpretive methods have been exhausted, the rule of lenity may require the ambiguity to be resolved in favor of the defendant.

The underlying principle is closely connected to legality:

People should not face criminal punishment under an interpretation of the law that the legislature did not clearly establish.

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12. Administrative Regulations

Administrative agencies can also create rules that affect conduct with legal consequences.

For example, agencies may regulate:

• environmental protection;
• workplace safety;
• food and drugs;
• financial markets;
• transportation;
• communications;
• and other highly regulated fields.

Some statutory schemes authorize criminal penalties for violating particular regulatory requirements.

But an important distinction must be maintained.

Administrative agencies generally derive their authority from legislation.

An agency does not possess unlimited independent power to declare any conduct criminal.

The legislature must provide a lawful basis for the regulatory scheme, and the resulting regulations must remain within the authority delegated by statute and consistent with constitutional limitations.

Administrative regulations can therefore operate as a source of legally binding requirements without becoming an unlimited independent source of criminal power.

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13. Local Ordinances

Criminal prohibitions can also arise at the local level.

Cities, counties, and other local governments may enact ordinances addressing matters such as:

• public safety;
• disorderly conduct;
• local property regulations;
• traffic offenses;
• public nuisance;
• licensing requirements;
• and other matters within their delegated authority.

The precise power of local governments depends upon state law and the structure of the relevant jurisdiction.

A local ordinance therefore cannot simply contradict a state criminal statute or exceed the authority granted to the local government.

Local criminal law is consequently part of a hierarchy of legal authority.

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14. State Constitutions

Every U.S. state has its own constitution.

State constitutions can provide protections affecting criminal law that are similar to, or sometimes broader than, protections found in the U.S. Constitution.

State constitutions may therefore influence:

• criminal legislation;
• punishment;
• searches and seizures;
• privacy;
• procedural rights;
• and other aspects of criminal justice.

A state criminal statute must comply with both applicable federal constitutional requirements and the state’s own constitutional requirements.

This creates an additional layer of protection for individuals accused of crimes.

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15. Treaties and International Law

International law occupies a more limited and specialized position within domestic American criminal law.

The United States enters into treaties concerning matters such as:

• extradition;
• transnational organized crime;
• terrorism;
• trafficking;
• corruption;
• and international cooperation in criminal matters.

International agreements can therefore influence how the United States addresses crimes involving other countries.

However, treaties do not simply create unlimited domestic criminal jurisdiction.

Their domestic legal effect depends upon constitutional rules, implementing legislation, and the nature of the particular treaty.

International law is therefore particularly important in areas where criminal conduct crosses national borders.

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16. International Criminal Law as a Distinct Field

International criminal law should also be distinguished from domestic criminal law.

International criminal law addresses particularly serious offenses that concern the international community, including:

• genocide;
• crimes against humanity;
• war crimes;
• and, under particular legal frameworks, aggression.

The sources of international criminal law can include:

• treaties;
• customary international law;
• international judicial decisions;
• and other recognized sources of international legal authority.

The development of international criminal law reflects the idea that certain acts are so serious that responsibility may extend beyond ordinary domestic jurisdiction.

This is a separate and specialized field, but it demonstrates that the concept of “criminal law” can operate at multiple legal levels.

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17. Customary Law

Custom can be an important source of law in many legal systems.

A customary rule develops through established practices accepted as legally obligatory.

Historically, custom contributed significantly to the development of common law.

Its role in modern American criminal law is much more restricted.

Criminal liability cannot ordinarily be based simply on the assertion that society has long considered particular conduct wrong.

The principle of legality requires a stronger legal foundation.

This is especially important because criminal punishment is more severe than many other forms of legal consequence.

A practice may be socially accepted without being sufficient by itself to establish a criminal offense.

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18. Legal Precedent and Stare Decisis

Judicial precedent operates through the doctrine of stare decisis, under which courts generally follow established legal principles from earlier decisions.

Precedent contributes to criminal law by promoting:

• consistency;
• predictability;
• stability;
• and uniform interpretation.

For example, once an appellate court establishes a controlling interpretation of a criminal statute, lower courts within the relevant jurisdiction generally must follow that interpretation unless it is changed or overruled.

But precedent is not equivalent to legislation.

A judicial decision interpreting an existing criminal statute does not necessarily give courts unlimited authority to create entirely new crimes.

The distinction between interpreting law and making criminal law is central to separation of powers.

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19. The Model Penal Code

An important influence on American criminal law is the Model Penal Code (MPC).

The Model Penal Code is not itself federal law and does not automatically apply in every state.

Instead, it is a model code developed by the American Law Institute to provide a systematic framework for criminal legislation.

It has had considerable influence on state criminal-law reform.

The Model Penal Code addresses subjects including:

• general principles of criminal liability;
• culpability;
• inchoate offenses;
• complicity;
• defenses;
• homicide;
• property offenses;
• and sentencing.

Its importance lies partly in its effort to bring greater conceptual consistency to criminal law.

Many state criminal statutes and judicial decisions have been influenced by Model Penal Code concepts, although the extent of adoption differs from state to state.

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20. Criminal Codes

Many jurisdictions organize criminal offenses into a criminal code.

A criminal code is a systematic collection of statutes defining offenses and related principles.

The federal government, for example, places federal criminal statutes primarily within Title 18 of the United States Code, although criminal provisions can also appear elsewhere in federal law.

State criminal codes similarly organize state offenses.

Codification has several advantages.

It makes criminal law more accessible.

It allows legislatures to organize related offenses systematically.

It can reduce uncertainty.

And it supports the principle that criminal prohibitions should be publicly identifiable.

A criminal code therefore represents more than a collection of offenses.

It is an attempt to create a coherent legal structure for criminal responsibility.

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21. The Hierarchy of Criminal-Law Sources

The different sources of criminal law do not all possess equal authority.

A simplified hierarchy in the United States can be understood as follows:

U.S. Constitution

The supreme legal framework governing federal and state governmental action.

Federal statutes

Criminal laws enacted by Congress within its constitutional authority.

State constitutions

The foundational legal instruments governing state governmental power.

State statutes

Criminal laws enacted by state legislatures.

Regulations and ordinances

Rules created under delegated governmental authority and within the limits established by higher law.

Judicial decisions

Authoritative interpretations of statutes, constitutions, regulations, and legal principles.

Historical common law

An important historical foundation of many criminal doctrines, but with a more limited role in modern statutory criminal systems.

This hierarchy is simplified because the American legal system is federal and highly complex.

Federal and state authority operate in parallel rather than forming a single vertical chain.

Nevertheless, the basic principle remains:

Lower-level legal rules cannot validly override higher-level law.

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22. Separation of Powers and the Creation of Crimes

The sources of criminal law are closely connected to the doctrine of separation of powers.

In a constitutional system, governmental authority is divided among different institutions.

Legislatures make laws.

Executives enforce laws.

Courts interpret laws.

This structure matters greatly in criminal law.

If judges could simply create new crimes whenever they considered particular conduct harmful, the distinction between lawmaking and adjudication would become blurred.

If prosecutors could decide independently what conduct should be criminal, the principle of legality would be undermined.

If executive agencies could create criminal prohibitions without legislative authority, delegated power could become effectively unlimited.

The requirement that criminal offenses have a lawful source therefore reinforces the constitutional distribution of governmental power.

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23. Sources of Criminal Law and the Rule of Law

The rule of law requires more than the existence of written statutes.

It requires a legal system in which governmental power is exercised according to established rules.

For criminal law, this means that:

• offenses should have a legal foundation;
• laws should provide meaningful notice;
• punishment should have a legal basis;
• courts should apply law rather than personal preference;
• prosecutors should operate within legal authority;
• and government officials should themselves be subject to legal constraints.

The source of a criminal prohibition is therefore inseparable from its legitimacy.

A government cannot simply announce after the fact that someone’s conduct was criminal.

The legal system must provide the relevant authority in advance.

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24. Why the Source of a Criminal Rule Matters

Knowing the source of a criminal rule can answer several practical questions.

Is the rule legally valid?

A criminal prohibition created without lawful authority may be unconstitutional or otherwise invalid.

Which court has jurisdiction?

Federal and state criminal laws can involve different courts and different jurisdictional requirements.

What interpretation controls?

A federal statute may be interpreted by federal courts, while a state statute is interpreted within the applicable state judicial system.

Can the legislature change the rule?

Usually yes, subject to constitutional restrictions.

Can a court overrule an interpretation?

Appellate precedent can change, although the applicable rules of precedent differ between jurisdictions.

Can an agency create the offense?

Only where lawful authority permits the relevant regulatory scheme and criminal consequences.

The question “Where does this rule come from?” is therefore one of the first questions a lawyer should ask when analyzing a criminal-law problem.

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25. A Practical Method for Identifying the Source of a Criminal Law

When confronted with a criminal-law question, the following sequence is useful.

Step 1: Identify the jurisdiction

Is the matter federal, state, local, or international?

Step 2: Identify the alleged offense

What specific crime is being charged?

Step 3: Locate the governing statute or legal provision

What provision actually defines the offense?

Step 4: Examine constitutional limitations

Does the statute comply with applicable constitutional requirements?

Step 5: Examine judicial interpretations

Have courts interpreted the relevant provision?

Step 6: Check applicable regulations or ordinances

Does a regulatory or local rule form part of the legal framework?

Step 7: Determine the applicable precedent

Which judicial decisions are binding on the court hearing the case?

Step 8: Consider defenses and limitations

Does another legal rule affect criminal responsibility?

This method prevents a common analytical mistake: treating a general statement about criminal conduct as though it were itself the legal source of criminal liability.

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26. What Is Not a Source of Criminal Law?

It is equally important to understand what does not, by itself, create criminal liability.

Public opinion

Society may strongly condemn conduct without that conduct being criminal.

Morality

Moral wrongdoing does not automatically become a criminal offense.

Police policy

Police departments enforce criminal law but do not ordinarily possess general authority to create crimes.

Prosecutorial preference

A prosecutor decides whether and how to pursue charges within lawful authority but cannot simply invent an offense.

Judicial personal belief

A judge cannot punish someone merely because the judge personally believes the conduct was wrong.

Media coverage

Public controversy does not create criminal liability.

Social custom alone

A social practice or tradition does not automatically establish a criminal offense.

These distinctions reinforce a fundamental principle:

Criminal liability must rest upon law, not merely upon disapproval.

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27. The Importance of Notice

One of the strongest reasons for clearly identifiable sources of criminal law is notice.

People need to know what the law prohibits before they can reasonably be expected to comply with it.

This is particularly important in criminal law because the consequences can be severe.

A vague or inaccessible criminal prohibition can undermine fairness.

If reasonable people cannot determine what conduct is prohibited, the law may raise serious constitutional and due-process concerns.

This is why doctrines concerning vagueness, legality, statutory interpretation, and fair notice are closely connected.

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28. Sources of Criminal Law and Technological Change

Modern technology creates new challenges for traditional sources of criminal law.

Consider conduct involving:

• artificial intelligence;
• cryptocurrency;
• digital assets;
• autonomous systems;
• cyberattacks;
• deepfakes;
• online fraud;
• and digital identity theft.

Technology can develop more rapidly than legislation.

This creates pressure to interpret existing laws in ways that address new forms of conduct.

But there is a boundary.

Courts must interpret existing criminal statutes according to recognized principles rather than simply declaring that technologically novel conduct is criminal because it resembles older wrongdoing.

This tension between legal certainty and technological adaptation will become increasingly important in modern criminal law.

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29. Sources of Criminal Law in Common-Law and Civil-Law Systems

The distinction between legal traditions is also important.

Common-law systems

Common-law systems historically gave judicial decisions a particularly significant role in developing legal principles.

The United States inherited much of its legal tradition from English common law, although modern American criminal law is predominantly statutory.

Civil-law systems

Civil-law systems generally place greater emphasis on comprehensive written codes enacted by legislatures.

Criminal offenses are typically defined in detailed statutory codes.

Judicial decisions remain important for interpretation but generally do not occupy exactly the same formal position as legislation.

The distinction should not be overstated.

Modern common-law jurisdictions rely extensively on legislation, while civil-law courts obviously interpret statutes.

Nevertheless, the different traditions illustrate two important approaches to the relationship between legislation, precedent, and legal reasoning.

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30. The Central Principle: No Criminal Liability Without Legal Authority

The many sources of criminal law can ultimately be reduced to one fundamental idea:

The state must have lawful authority before it can punish conduct as a crime.

That authority may come from legislation, operating within constitutional limits.

It may be interpreted through judicial decisions.

It may be supplemented by properly authorized regulations or ordinances.

It may be influenced by historical common-law principles.

And in specialized contexts, international law may provide part of the relevant legal framework.

But criminal punishment cannot rest merely on morality, public anger, administrative convenience, or governmental preference.

This requirement protects individuals from arbitrary prosecution and reinforces the legitimacy of the criminal justice system.

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31. Conclusion

Criminal law derives its authority from recognized sources of law.

In modern American criminal law, legislation is the principal source of criminal offenses. Congress creates federal crimes within its constitutional authority, while state legislatures create most state crimes. Constitutions provide the higher legal framework within which criminal legislation must operate.

Judicial decisions play a different but essential role. Courts interpret statutes, resolve constitutional questions, establish precedent, and determine how criminal rules apply to particular circumstances. They therefore shape the practical meaning of criminal law without possessing unlimited authority to invent new offenses.

Administrative regulations and local ordinances can also form part of the criminal-law framework where validly authorized by higher law.

The common law remains historically important, particularly because many modern doctrines developed from common-law principles. The Model Penal Code has also influenced American criminal-law development without itself functioning as universally binding law.

International law and treaties become particularly significant when criminal conduct crosses national borders or involves international crimes.

Underlying all of these sources is the principle of legality: no person should be punished for conduct unless the legal system has established a lawful basis for treating that conduct as criminal.

The sources of criminal law therefore perform two functions at once.

They create and define criminal prohibitions, but they also limit governmental power.

That second function is just as important as the first.

A criminal justice system is legitimate not merely because it can punish wrongdoing, but because it can demonstrate where its authority comes from.

The essential question is therefore not simply:

“Is this conduct wrong?”

It is:

“What law makes this conduct criminal, and does that law have legitimate authority?”

That question lies at the foundation of every sound analysis of criminal responsibility.

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Key Takeaways

• Sources of criminal law are the recognized legal authorities from which criminal rules derive their validity.
• In modern American criminal law, legislation is the principal source of criminal offenses.
• Federal crimes are primarily created by Congress, while state crimes are primarily created by state legislatures.
• The U.S. Constitution limits what government may criminalize and how criminal punishment may be imposed.
• State constitutions can provide additional protections beyond federal constitutional requirements.
• Judicial decisions interpret criminal statutes, resolve constitutional questions, and establish binding precedent within applicable jurisdictions.
• Common law historically played a major role in developing criminal doctrines but has a more limited role in modern statutory criminal law.
• Administrative regulations can contribute to criminal-law enforcement when properly authorized by legislation.
• Local ordinances may establish offenses within the authority delegated to local governments.
• The Model Penal Code is an influential model rather than a universally binding criminal code.
• Treaties and international law can become important in transnational and international criminal matters.
• The principle of legality requires criminal prohibitions and punishments to have a lawful basis.
• Criminal liability cannot be based merely on morality, public opinion, prosecutorial preference, or social disapproval.
• The sources of criminal law do more than create criminal prohibitions: they also limit the state’s power to punish.
• Understanding the source of a criminal rule is one of the first steps in determining whether the rule is valid, applicable, and enforceable.

Frequently Asked Questions

What is the primary source of criminal law in the United States?

The principal source of modern American criminal offenses is legislation. Federal crimes are generally created by Congress, while state crimes are primarily created by state legislatures.

Is the Constitution a source of criminal law?

The Constitution is not generally a source of ordinary criminal offenses in the same way that a criminal statute is. Instead, it establishes higher legal rules and constitutional limitations that govern criminal legislation and punishment.

Can judges create crimes?

Modern American courts generally do not possess unlimited authority to create new criminal offenses. Their primary role is to interpret and apply existing law. This reflects legality and the separation of powers.

What is common-law criminal law?

Common-law criminal law refers historically to offenses and doctrines developed through judicial decisions rather than comprehensive legislative codes. Many American criminal-law doctrines originated in English common law, although modern U.S. criminal offenses are predominantly statutory.

What is the Model Penal Code?

The Model Penal Code is a comprehensive model of criminal law developed by the American Law Institute. It is not itself universally binding law but has substantially influenced criminal legislation and judicial reasoning in the United States.

Can an administrative agency create a crime?

An agency generally cannot independently create unlimited criminal offenses. Criminal consequences associated with regulations must rest upon lawful legislative authority and comply with constitutional limitations.

Can a city create criminal offenses?

Local governments may enact criminal or quasi-criminal ordinances when state law gives them the authority to do so. Local governments cannot ordinarily exceed their delegated authority or enact rules that conflict with controlling higher law.

What does “nullum crimen sine lege” mean?

The Latin phrase means “no crime without law.” It expresses the principle that conduct should not be punished as criminal unless there is a lawful basis defining it as an offense.

Why is legality important in criminal law?

Legality protects people from arbitrary punishment by requiring criminal prohibitions to have a legal foundation and, generally, to provide adequate notice of prohibited conduct.

What is the rule of lenity?

The rule of lenity is a principle of statutory interpretation under which a genuinely ambiguous criminal statute may, after applicable interpretive principles have been exhausted, be interpreted in favor of the defendant.

Can morality create criminal liability?

No. Conduct may be morally condemned without being criminal. Criminal liability requires a recognized legal basis for treating the conduct as an offense.

What role do courts play in criminal law?

Courts interpret criminal statutes, determine how legal rules apply to facts, resolve constitutional challenges, and establish judicial precedent. They are essential to the operation of criminal law even though their lawmaking authority is constrained by constitutional principles.

What is the difference between a statute and a judicial decision?

A statute is enacted by a legislature and establishes legal rules through the legislative process. A judicial decision resolves a legal dispute and may establish precedent or interpret an existing legal rule.

Are federal and state criminal laws the same?

No. Federal and state governments possess different sources of criminal-law authority, and their statutes, jurisdictional requirements, procedures, and punishments can differ substantially.

Why does the source of criminal law matter?

The source determines whether a criminal rule has lawful authority, which institution created or interpreted it, what jurisdiction it applies to, and whether it is subject to particular constitutional or statutory limitations.