Besides the concept of the Constitution, there is also the all-important concept of ‘Constitutionalism’. Modern political thought draws a distinction between ‘Constitutionalism’ and ‘Constitution’. A country may have the ‘Constitution’ but not necessarily ‘Constitutionalism’. For example, a country with a dictatorship, where the dictator’s word is law, can be said to have a ‘Constitution’ but not ‘Constitutionalism’. The underlying difference between the two concepts is that a Constitution ought not merely to confer powers on the various organs of the government, but also seek to restrain those powers. Constitutionalism recognizes the need for the government but insists upon limitations being placed upon governmental powers. Constitutionalism envisages checks and balances and putting the powers of the legislature and the executive under some restraints and not making them uncontrolled and arbitrary.

Unlimited powers jeopardize the freedom of the people. As has been well said:
power corrupts and absolute power corrupts absolutely. If the Constitution confers
unrestrained power on either the legislature or the executive, it might lead to
an authoritarian, oppressive government. Therefore, to preserve the basic freedoms
of the individual, and to maintain his dignity and personality, the Constitution
should be permeated with ‘Constitutionalism’; it should have some in-built
restrictions on the powers conferred by it on governmental organs.
‘Constitutionalism’ connotes in essence limited government or a limitation on
government. Constitutionalism is the antithesis of arbitrary powers. ‘Constitutionalism’
recognizes the need for a government with powers but at the same time
insists that limitations be placed on those powers. The antithesis of Constitutionalism
is despotism. Unlimited power may lead to an authoritarian, oppressive,
government that jeopardizes the freedoms of the people. Only when the Constitution
of a country seeks to decentralize power instead of concentrating it at
one point, and also imposes other restraints and limitations thereon, does a country
have not only ‘constitution’ but also ‘constitutionalism’.
‘Constitutions spring from a belief in limited government. According to
SCHWARTZ, in the U.S.A., the word Constitution means “a written organic instrument,
under which governmental powers are both conferred and circumscribed”.
He emphasizes that “this stress upon grant and limitation of authority is
fundamental”. As PROFESSOR VILE has remarked:
“Western institutional theorists have concerned themselves with the problems
of ensuring that the exercise of governmental power, which is essential to
the realization of the values of their societies should be controlled in order that
it should not itself be destructive of the values it was intended to promote.”
The idea of Constitutionalism is not new. It is embedded deeply in human
thought. Many natural law philosophers have promoted this idea through their writings.

Some of these philosophers are: ACQUINAS, PAINE, LOCKE, GROTIUS AND
ROUSSEAU. The Magna Carta (1215) strengthened the traditional view that law is
supreme. As observed by ARTHUR SUTHERLAND, “The Great Charter was obviously
a cherished standard, a welcome assurance that people could set some limitation on
the arbitrary power of the king.”
A written Constitution, an independent judiciary with powers of judicial review,
the doctrine of rule of law and separation of powers, free elections to legislature,
accountable and transparent democratic government, Fundamental Rights of the
people, federalism, decentralization of power are some of the principles and norms
which promote Constitutionalism in a country.