Q: "Right to Equality is dynamic Concept ". Explain with reference to Article 14 of Indian Constitution ?

Ans: A.V. Dicey developed the concept of Rule of Law in his book ' The constitution of England '.
According to rule of law, the law make same effect and treat equally to everyone in same circumstances.
According to rule of rule, law treats equally to everyone and no one is above law.
Both government and citizens will get equal treatment by law in accordance with rule of law.
This concept was seen in Indian Constitution in two places i.e.,one is in preamble and other is in Article 14.
Article 14 says two things i.e., prohibit unequal treatment which is negative approach and demands equal treatment which is positive approach.
To prohibit unequal treatment is equality before law and to demand equal treatment is equal protection of laws.
Article 14(1) i.e equality before law is an English Law Concept. The rule of law will treat equally for any act or omission in equality before law.
The example is lady Justice.  The lady Justice is blind folded which means that everyone is equal before law.
Article 14(2) mentions equal protection of laws which is American Concept and it mentions that it is not necessary that there will be a universal application of any law.
It is not necessary that a particular law gets applied on different persons in a similar way. According to law both the child of 5 years and 10 years get same food and education facility but the quantity of food and level of education will be different for 5 year and 10 year child.
Thus, equality before law is a generic concept and is used in general way whereas  equal protection of law is a specific concept.
Equal protection of law says that public welfare is must for equal protection of law.
Equal protection of law mentions that classification is must for public welfare.
Classification will be on the basis of caste, sex and religion.
To prevent this classification from undue advantage,  there is test which comprises of two conditions i.e., Intelligible Differentia and Rational Nexus.
In accordance with Intelligible differentia, there must be intelligent reason for the classification of two groups.
According to rational nexus, the classification is performed on the basis of purpose and result. There is a purpose of classification and a person would like to get some result on the basis of classification.
So, according to rational nexus there must be nexus or connection between purpose and result for better classification.
In conformity with rational nexus, the classification is performed on the basis of some purpose and when the purpose is fulfilled,  it would give desired result.
Thus,  rational nexus generate the connection between the classification and desired end.
It was the old doctrine of right to equality.
This old doctrine which comprises of above two test factors was mentioned in the case of State Of Bombay And Another vs F.N. Balsara on 25 May, 1951.
The  Supreme Court found this old doctrine of negative and restrictive approach.

So, in case of E.P. Royappa V. State of Tamil Nadu, AIR 1974 SC 555, the honourable Supreme Court held the equality is a dynamic concept and it can not be cribbed, cabined or confined with traditional limits.
This new doctrine is of dynamic and of activist nature.
According to this new doctrine,  the equality before law is not only rule of law but it would also include the principles of natural justice.
The same view was adopted in case of Menaka Gandhi V. Union of India, AIR 1978 SC 597.
Article 14 ensures fairness and equality.
Reasonableness is an essential element of equality or non- arbitrariness.
The old doctrine gave two tests of Intelligible differentia and rational nexus. In these two tests, if we add reasonableness, it would generate new doctrine.  The new doctrine targets arbitrariness.
Equality and Arbitrariness are sworn enemies.
If anything is arbitrary, it opposes equality.
This is the reason why Article 14 doesn't exist alone and it is connected to Article 19 and Article 21 to act in conformity with new doctrine of right to equality.  This rule is also called golden triangle rule.