Constitutionalism can generally be regarded as the idea that governments exercising state power absolutely obey the provisions of the constitution and the establishment of a system of such exercise. In other words, it means that the governments cannot exercise the power without limitation, but within the framework of the constitution exactly enacted. This kind of idea is known in connection with the political ideology of the English philosopher John Locke. The perceptions and the proposed ideas in his theory of social contract are the first systematic ideas and the basic principles of constitutionalism. The concept of ‘limited government’ which is the core part of liberalism in his political philosophy is the summarized statement of constitutionalism. The idea of this ‘limited government’ means that every government exercising state power can only use such power within the provisions of the constitution. 

The limited government not only has no authority to override the constitution but also its legitimacy, in other words, the rights of its authority, depend on whether it follows the provisions of the constitution.

To make sure that a government exercises its power in compliance with the provisions of the constitution and does not break its principles and limitations, it needs to create some institutional arrangements. The important institutional arrangements are:

1. The entrenchment of the constitution
2. A Written constitution and
3. Separation of powers [1]

1. Entrenchment of the constitution

To limit the power of a government according to the constitution, it must enact the values that should not be violated. It is important to entrench the constitution so that the government cannot easily amend it while it is in power. These provisions of limitation of the power must be enacted so that they are difficult to amend.

The limitations on the power of the government are human rights, citizen rights, and freedoms in general. ‘Entrenchment’ means that the rights and freedoms in the bill of rights respectfully approved are made difficult to amend. It also means ‘the special provisions’ that the president, or the veto of the administration or the majority of the legislature cannot amend these rights with their consent. It will be meaningless if the administration or the legislature can amend these provisions without any difficulties.  

2. A Written Constitution

If the values that limit the power of the government are not provided in the written constitution with deep respect, these values do not actually exist. as said by Rubenfeld, a scholar in the Standford Encyclopedia of Philosophy.[2] The constitution in words is concise, and it can be assessed more precisely on whether a government has violated its limitations or not. Although it can be argued with the example of England, which has no written document of the constitution and is practicing strong constitutionalism, this example should be regarded as exceptional. Only if the limitations are enacted in the written constitution, uncertainties, discretionary definition of it, its consistency, exclusion of it, and the gradually deteriorated changes can be avoided.

3. Separation of Powers

According to the perception of the French philosopher Charles-Louis de Secondat, Baron de La Brède et de Montesquieu, without separation of powers on sovereignty among the legislature, administration, and justice, if all these three powers are granted to only one person or only the administrative body by the constitution, this kind of administrative system is called a dictatorship. Holding this perception by the political leaders who drafted the Constitution of the United States of America, the provisions of the separation of powers were incorporated into it in 1989. If the limitations on power are enacted without any separation of powers in the constitution, these limitations lack substance whenever the administrator breaks them because no one has the power to make checks and balances with each other. Moreover, because the power of justice will be in the hands of the administrator, the definition of the limitations will be defined by himself or herself at his or her own discretion, in which his or her actions comply with the constitution and do not violate them. Although there is a constitution in a country in which all the powers are granted to someone or one body, it can be assumed that there is no constitutionalism in this kind of constitutional system.

Constitutionalism and Rule of Law

The main concept of the rule of law means, in brief, that members of the government who are ruling a country must exercise their power and do their every action in accordance with laws. In other words, even if human beings are ruling the country, it should be as if the laws rule the country. The authorities have no right to perform something at their own discretion except for authorized actions by law. Furthermore, they must observe their conduct which is permitted by law, while performing their actions. They must do their responsibilities as if they have no personal feelings or beliefs on them. In this understanding of the concept of the rule of law, it is always regarded as looking like the concept of constitutionalism.