"The judicial Power of the United States, shall be vested in one supreme Court, and in such inferior Courts as the Congress may from time to time ordain and establish." - Article III, U.S. Constitution

Glossary of Legal Terms
Equal Protection
Due Process
Structure Of The Courts
(This section is based almost entirely on material from the Administrative Office of the U.S. Courts.)

Throughout the United States there are two judicial systems. One system consists
of a state court system established under the authority of the state governments.
The other is the U.S. Supreme Court and the federal court system, created by Congress
under the authority of the Constitution of the United States.
The federal court system consists of the district courts, appellate courts and the Supreme Court.

District Courts

Most federal cases are initially tried and decided in the U.S. district courts, the
federal courts of general trial jurisdiction. There are 94 district courts in the 50
states, the District of Columbia, the Commonwealth of Puerto Rico, and the
territories of Guam, the U.S. Virgin Islands, and the Northern Mariana Islands.
A district may itself be divided into divisions and may have several places where the court hears cases.
Each district court also has a bankruptcy unit. With the exception of the three territorial courts,
all district court judges are appointed for life by the President with the advice and consent of the Senate.
Congress authorizes judgeships for each district based in large part on the
caseload. There are 649 district court judges.

Appellate Courts

The intermediate appellate courts in the federal judicial system are the courts of
appeals. Twelve of these courts have jurisdiction over cases from certain
geographic areas. The Court of Appeals for the Federal Circuit has national
jurisdiction over specific types of cases, usually involving patents and minor claims against the federal government.

The First through Eleventh Circuits each include three or more states (see map).
The U.S. Court of Appeals for the District of Columbia hears cases arising in the District of Columbia and has appellate jurisdiction assigned by Congress in legislation concerning many departments of the federal government As in the district courts, the judges who sit on the courts of appeals are appointed
for life by the President with the advice and consent of the Senate. Each court of
appeals consists of six or more judges, depending on the caseload of the courts.
There are 167 judges on the 12 regional courts of appeals.
 

U.S. Supreme Court
The Supreme Court of the United States consists of 9 Justices appointed for life
by the President with the advice and consent of the Senate.
One justice is appointed as the Chief Justice and has additional administrative duties
related both to the Supreme Court and to the entire federal court system. Each
justice is assigned to one or more of the courts of appeals for emergency responses.

The Supreme Court meets on the first Monday of October each year and usually
continues in session through June. The Supreme Court receives and disposes of
about 5,000 cases each year, most by a brief decision that the subject matter is
either not proper or not of sufficient importance to warrant review by the full
court. Cases are heard en banc, which means by all the justices sitting together in
open court. Each year the court decides about 150 cases of great national
importance and interest, and about three-fourths of such decisions are announced
in full published opinions.

State Courts

The state courts have general, unlimited power to decide nearly every type of case,
subject only to the limitations of the U.S. Constitution, their own state
constitutions, and state law. The state and local courts are located in virtually
every town and county and are the courts with which citizens most often have
contact. These courts handle most criminal matters and the great bulk of legal
business concerning probate of estates, marital disputes, dealings in land,
commercial contracts, and other day-to-day matters.

Since all citizens are always simultaneously present in a State and in the United States they are
subject to the dual jurisdiction of Federal and State Courts and have protections from both the
Federal and State Constitution. The State Constitution may provide more protections than the
Federal Constitution, but it may not provide less. Similarly, if a Federal Court strikes down a statute
based upon the Federal Constitution, the State Courts can not revive the statute. The question of whether
to challenge a particular statute in Federal or State Court is an exceedingly complicated one that we will
not deal with.

Equal Protection

Section. 1. All persons born or naturalized in the United States and subject to
 the jurisdiction thereof, are citizens of the United States and of the State
 wherein they reside. No State shall make or enforce any law which shall
 abridge the privileges or immunities of citizens of the United States; nor shall
 any State deprive any person of life, liberty, or property, without due process
 of law; nor deny to any person within its jurisdiction the equal protection of
 the laws.
--Fourteenth Amendment, Section 1
 
The Equal Protection Clause is the portion of the Fourteenth Amendment to the
U.S. Constitution that prohibits discrimination by state government institutions.
The clause grants all people "equal protection of the laws," which means that the
states must apply the law equally and cannot give preference to one person or class of persons over another.

The technique which the Court(s) use(s) to apply the Equal Protection Clause is the doctrine of  scrutiny of suspect classifications.

When a statute is challenged before a Court on an equal protection basis the argument is being made that one class of people is being treated differently than another class of people. Of course, all laws do this to some extent. The question for the court is
whether the law is "narrowly tailored" to "further a legitimate governmental purpose" and whether there is
a "rational basis" for the classification. The Court has upheld classifications such as income, height, public conduct and  appearance . Over time the Court has treated certain classifications with more suspicion.
Characteristics which the Court requires more than just a rational basis in order to uphold the law are called suspect classifications.
For example, classifications based on race are met with strict scrutiny, which means that the Court will look very very carefully to make sure that the statute is not based on prejudice, or attempting to promote an illegitimate aim. Strict scrutiny is often referred to as  "strict in theory, fatal in fact." This means that very few laws pass the strict scrutiny test. Interestingly, in the first case in which the concept of strict scrutiny was introduced, Korematsu v. United States, 323 U.S. 214 (1944), the racial classification (of interning Japanese American during World War II) was actually upheld by the Court. Classifications based on national origin are also met with strict scrutiny, usually. When the federal government is making the classification, the rational basis test is commonly used. However, state classifications have been invalidated repeatedly.

Other examples of suspect classifications are sex and illegitimacy, which are met with "intermediate scrutiny."

Due Process
"No person shall be held to answer for a capital, or otherwise infamous crime,
 unless on a presentment or indictment of a Grand Jury, except in cases arising
 in the land or naval forces, or in the Militia, when in actual service in time of
 War or public danger; nor shall any person be subject for the same offence to
 be twice put in jeopardy of life or limb; nor shall be compelled in any criminal
 case to be a witness against himself, nor be deprived of life, liberty, or
 property, without due process of law; nor shall private property be taken for
 public use, without just compensation."
-- Fifth Amendment

"All persons born or naturalized in the United States and subject to
 the jurisdiction thereof, are citizens of the United States and of the State
 wherein they reside. No State shall make or enforce any law which shall
 abridge the privileges or immunities of citizens of the United States; nor shall
 any State deprive any person of life, liberty, or property, without due process
 of law; nor deny to any person within its jurisdiction the equal protection of
 the laws."
- Fourteenth Amendment, Section 1

The words "due process" appear in the Constitution in both the Fifth and Fourteenth Amendments.
They refer to the idea that laws and legal proceedings must be "fair." The Due Process Clause of the
Fifth Amendment is a prohibition on arbitrary or capricious governmental action by the Federal Government.
The Due Process Clause of the 14th Amendment has been interpreted by the USSC to apply those same standards to the individual States.

The Constitution guarantees that the government (State or Federal) cannot take away a person's basic rights to "life, liberty or property, without due process of law" (appears in both 5th and 14th Amendments.)
Courts have issued numerous rulings about what concepts are incorporated by the words "life, liberty or property" mean in particular cases.
Of particular interest is the concept of substantive due process. This idea is that the protections granted by the Due Process Clause are substantive or expansive.

Substantive Due Process is the notion that the Court(s) can broadly interpret laws to see whether they are fair or not.
In particular, the Court(s) will be more likely to invalidate laws that infringe upon fundamental rights.

The difference between Substantive Due Process and Equal Protection is the difference between laws which restrict a right for "all" and laws which seek to carve out a "discrete and insular group" and treat them differently. If the right being abridged is fundamental or if the group being singled out is based on a suspect classification (race, gender/sex, illegitimacy, national origin) then it is more likely than not the law will not survive judicial review and will be invalidated by the court.

One of the most controversial examples of fundamental rights which flow from the judicial theory of substantive due process is the right of  privacy. The right of privacy is the right "to be left alone" by the Government in order to make decisions about intimate personal affairs. One of the reason's this right is controversial is that it can be found nowhere in the text of the Constitution, though many observers believe it follows directly from an expansive reading of the Due Process Clause.

Another relevant fundamental right which shows up in discussions of substantive due process is the right to marry.
Other rights which have been declared fundamental by the United States Supreme Court are

• the right to vote
• the right to public education
• the right to (interstate) travel
• the right to establish a home and bring up children
• the right to privacy (includes abortion and contraception)

Interestingly, the "right to die" and the "right to commit homosexual sodomy" have recently been found not to be included in the Due Process Clause.
 
When the Court determines that it is dealing with a fundamental right that is being infringed it looks at the law being challenged with heightened scrutiny, often leading to strict scrutiny, depending on the degree to which the fundamental right is being burdened by the state.