Ch1. Introduction to Criminal Law — Foundations and Basic Principles

What Is Criminal Law?

Criminal Law:
The body of law that defines which acts constitute crimes
and prescribes the punishments for those acts.

Functions of Criminal Law:
Protective function: safeguards legally protected interests
  (life, property, liberty, etc.)
Restraining function: protects individuals from arbitrary
  government punishment power

The Criminal Justice Framework:
Substantive criminal law: defines crimes and punishments
  (e.g., Model Penal Code, federal criminal statutes)
Criminal procedure: governs investigation, prosecution,
  and trial (4th, 5th, 6th, 14th Amendments; Federal Rules
  of Criminal Procedure)

Categories of Punishment:
Capital punishment: death penalty
Incarceration: imprisonment (determinate / indeterminate /
  life without parole)
Fines and forfeiture: monetary penalties, asset forfeiture
Collateral sanctions: loss of civil rights, professional
  licenses, voting rights

The Principle of Legality

Nullum crimen sine lege / Nulla poena sine lege:
"No crime without law; no punishment without law."
Prevents arbitrary exercise of government power to punish.

Derived Principles:

① No common-law crimes (in most US jurisdictions):
   Crimes must be defined by statute (or valid ordinance).
   Federal common-law crimes are abolished.

② No ex post facto punishment:
   A person may only be punished under the law in force
   at the time of the act.
   (US Const. Art. I §§ 9–10; retroactive leniency is
   generally permissible)

③ No punishment by analogy:
   Courts may not extend criminal statutes by analogy
   to cover conduct not clearly within their text.

④ Void-for-vagueness doctrine:
   A statute is unconstitutional if it fails to give
   fair notice of what conduct is forbidden (5th / 14th
   Amendment due process).

Effect of Violation:
A statute violating the legality principle → void
(struck down by courts under constitutional review)

Scope of Criminal Law

Territorial Jurisdiction (Domestic):
Territoriality (default): federal/state law applies to
  crimes committed within US territory.
Nationality principle (supplemental): US law may apply
  to US nationals committing certain crimes abroad
  (e.g., RICO extraterritorial provisions, MDLEA).
Protective principle: US law applied when foreign conduct
  threatens US national interests (e.g., counterfeiting).
Universality principle: US courts may try certain
  international crimes regardless of where committed
  (e.g., piracy, genocide, torture — 18 U.S.C. §§ 2340–2340A).

Temporal Scope:
The law in effect at the time of the act governs.
Retroactive application of a more lenient law: generally
  permissible (1st Savings Bank v. United States;
  see also 18 U.S.C. § 3582 retroactive relief).

Theories of Punishment

Retribution:
Punishment is proportional to the offense ("an eye for
an eye"). Punishment = realization of justice.
Foundational in US sentencing guidelines (just deserts).

Special Deterrence:
Rehabilitating or incapacitating the individual offender.
Punishment = preventing recidivism (parole, treatment
programs, incapacitation).

General Deterrence:
Warning to the public at large.
Punishment = discouraging potential offenders.

Modern US Approach:
18 U.S.C. § 3553(a) lists purposes of sentencing:
just punishment, deterrence, incapacitation, rehabilitation.
Emphasis has shifted toward rehabilitation and
evidence-based recidivism reduction.

Legality Principle — 4 Corollaries ★★★★★ : No common-law crimes · no ex post facto punishment · no analogy · vagueness void. Memory tip: Law must be Written, Prospective, Clear, and Specific (WPCS).

Territoriality as Default ★★★★★ : Federal and state criminal law applies primarily within US territory. Nationality, protective, and universality principles are exceptions. Memory tip: Default = territory; exceptions = nationality / protective / universal.

Retribution vs. Deterrence ★★★★☆ : Retribution = backward-looking (punish past wrong). Deterrence = forward-looking (prevent future crime). Memory tip: Retribution = past; Deterrence = future.

Practice Quiz

Q. What does the “no punishment by analogy” corollary mean in practice?

Courts cannot extend a criminal statute to conduct that falls outside its plain text simply because the conduct is similar to what is covered. Example: a statute punishing car theft cannot be applied to motorcycle theft by analogy. Criminal statutes are strictly construed against the government (rule of lenity).

Q. How does substantive criminal law differ from criminal procedure?

Substantive criminal law (e.g., Model Penal Code, Title 18 U.S.C.) defines what conduct is criminal and what punishment attaches. Criminal procedure (4th–6th Amendments, Federal Rules of Criminal Procedure) governs how the government may investigate, charge, try, and punish a defendant. Without substantive law there is nothing to enforce; without procedural law the government cannot lawfully enforce it.