According to the classification of the constitutions a constitution may be unitary or federal . unitary form of constitution the powers are centralized in a central govt only, but in the form of federal constitution there is division of powers between the center & state governments.and both are independent in their own spheres.

What is federalism 

The word federalism derived from the Latin  word “feodus “which means agreement. Elements of federalism were introduced into modern India by the govt of India act of 1919 .which separated powers between the center and states. The word federation is not mentioned in the Indian constitution .India is a federal system but with more tilt towards a unitary system of government. It is sometimes considered a quasi-federal system as it has features of both a federal and a unitary system. Article 1 of the Indian Constitution states, ‘India, that is Bharat, shall be a union of states’

Federalism is a system of govt in which two sets of governments operate on the same group of people. That means controlled by two levels of govt. The central govt usually oversee the issues of the entire country,other look after the issues of local concern. 

Purpose of the federalism ;

1. Preventing concentration of power in the hand of one tire of govt .
2. Generating strength of the nation through the union .

Essential characteristics of a federal constitution .

A federal constitution has the following essential characteristics are

1. Distribution of powers 
2. Supremacy of constitution 
3. A written constitution 
4. Rigidity
5. Independent judiciary 
6. Dual citizenship 
7. Division of funds

1)  Distribution of powers –

                  The distribution of powers is an essential feature of federalism . Federalism means the distribution of powers of the state among the number of coordinate bodies each originating in and controlled by the constitution.

2)  Supremacy of Constitution –

                 A federal state derives its existence from the constitution.  Hence, every power, executive, legislative or judicial whether it belongs to the nation or the individual state is subordinate to and controlled by the constitution.  The constitution in a federal state constitute the supreme law of the land.  According to Prof. Where that those two institutions – the supreme constitution and the. written constitution are then, essential institutions to a federal government. The Supermacy of constitution is essential if a government is to be federal. 

3) A written constitution –

        A federal constitution must almost necessarily to be a written constitution. The foundations of a federal state are complicated contracts. It will be practically impossible to maintain the supremacy of the constitution unless the, terms of the constitution have been r reduced into writing. 

4) Rigidity –

         A natural of a written constitution is its rigidity . A constitution which is the supreme law of land must also be rigid.  In a rigid constitution the procedure of amendment is very complicated and difficult. This doesn’t mean that the constitution should not be legally unalterable. It simply means that the power of amending of the constitution should not be remain exclusively with either the central or state governments. A constitution of a country is considered to be the permanent document.  It is the supreme law of land. The Supremacy of the constitution can only be maintained if the method of amendment is rigid.

5) Authority of courts –

                   In a federal state the legal supremacy of the constitution is essential for the existence of federal system. The very nature of the federal state involves a division between the central and the state governments under the framework of the constitution. It is therefore,  essential to maintain this division of powers between the two levels of governments. This must be done by some independent and impartial authority above and beyond the ordinary bodies whether federal or state legislature or State legislature  existing  under the constitution.  The judiciary has, in a federal polity , , the final power to interpret the constitution and guard the entrenched provisions of the constitution.

6) Dual citizenship

The Constitution of India does not allow holding Indian citizenship and citizenship of a foreign country simultaneously. Based on the recommendation of the High Level committee on Indian Diaspora, the Government of India decided to grant Overseas Citizenship of India (OCI) commonly known as ‘dual citizenship’.

7) Division of Funds

While there is power sharing between the two levels of government, there should also be a system in place for revenue sharing. Both levels of government should have their own autonomous revenue streams. Because if one such government depends on the other for funds to carry out its functions, it really is not autonomous in its true nature.

India – A Federal State

India is a federal country. But not once in the constitution is the word “federation” ever mentioned. Instead what is said is that India is a “Union of States’.Actually many historians believe that India is a quasi-federal country. It means it is a federal state with some features of a unitary government. Let us see the reasons.

The constitution of India has essentially prescribed a federal state of government. As you already know we have several levels of government, The Government at the center, which id the Lok Sabha and the Rajya Sabha. Then the various state governments, the Vidhan Sabhas, and the Vidhan Parishad. And finally, we have the Municipal Corporations and the Panchayats, which are forms of local governance.

Our constitution makes a clear demarcation about legislative powers and jurisdictions. It is done through the three lists.

• Union List: This includes subjects that carry national importance, like defense, finance, railways, banking etc. So such subjects only the Central Government is allowed to make laws.
• State List: Includes all matters important to the functioning of a particular trade like transport, Trade, Commerce, agriculture etc. The state government is the deciding authority for framing laws on these subjects
• Concurrent List: This list includes topics on which both the Union and the state government can make laws. These are related to education, forests, trade unions etc. One point to be noted is if the two governments are in conflict with these laws, the decision of the Union Government will prevail, It is the final authority.