The Fifth Amendment’s Due Process Clause has two aspects: procedural
and substantive. Procedural due process is concerned with the process by
which legal proceedings are conducted. It requires that all persons who
will be materially affected by a legal proceeding receive notice of its
time, place, and subject matter so that they will have an adequate
opportunity to prepare. It also requires that legal proceedings be
conducted in a fair manner by an impartial judge who will allow the
interested parties to present fully their complaints, grievances, and
defenses. The Due Process Clause governs civil, criminal, and
administrative proceedings from the pretrial stage through final appeal,
and proceedings that produce ARBITRARY or capricious results will be overturned as unconstitutional.

SUBSTANTIVE DUE PROCESS is concerned with the content of particular laws that are applied during legal proceedings. Before WORLD WAR II,
the U.S. Supreme Court relied on substantive due process to overturn
legislation that infringed on a variety of property interests, including
the right of employers to determine the wages their employees would be
paid and the number of hours they could work. Since World War II, the
Court has relied on substantive due process to protect privacy and
autonomy interests of adults, including the right to use contraception
and the right to have an ABORTION.

The line separating procedure from substance is not always clear. For
example, procedural due process guarantees criminal defendants the
right to a fair trial, and substantive due process specifies that 12
jurors must return a unanimous guilty verdict before the death penalty
can be imposed. The concepts of substantive and procedural due process
trace back to English law. The MAGNA CHARTA
provided, “No free man shall be seized, or imprisoned, or disseised, or
outlawed, or exiled, or injured in any way … except by the lawful
judgment of his peers, or by the law of the land” (art. 39). According
to eminent English jurist SIR EDWARD COKE, law of the land and due process of law were interchangeable terms that possessed both procedural and substantive meaning.

The American colonists followed the English tradition of attributing
substantive and procedural qualities to the concepts of due process and
the law of the land. Maryland and Massachusetts, for example, equated
the two concepts with colonial COMMON LAW
and legislation regardless of their procedural content. On the other
hand, Virginia, Pennsylvania, and Vermont all passed constitutional
provisions identifying the law of the land with specific
procedural safeguards, including the right against self-incrimination.
Thus, when the Due Process Clause was submitted to the state conventions
for ratification, it was popularly understood to place procedural
requirements on legal proceedings as well as substantive limitations on
the law applied in those proceedings.