Schools of jurisprudence

Jurisprudence is the study or theory of law. It aims at defining the law and its origins. Jurisprudence aims at defining the nature and theory of law. It examines its origins and sources. Various different theories have been propounded to explain the nature, source and authority of law.
The various schools of jurisprudence are as follows:
(1) Natural law: natural law was propounded by the philosophers and religious scholars as law having divine origin. Under this school, there is very little difference between law and morality. It was implied that law can only be discovered by rational deductions from the nature of man. It proposes that law is the inherent moral values in an individual that are discovered by the deductions and introspection. The various proponents of this theory were Aristotle, Thomas Acquinas, Thomas Hobbes.
(2) Analytical or positive school: as opposed to the natural law, the analytical school does not take morality into consideration. The question, what law is? is the subject of discussion and not what law ought to be?
Amongst the proponents of the analytical law, Bentham gave his utilitarian theory and proposed the hedonistic calculus, which states that law is propounded by a higher authority for the greatest good of the greatest number.
As per Austin, law is the command of sovereign backed by sanction. For him, law comprises of order or command from a higher authority along with the power to punish for its disregard. The application of force is an important aspect in determining the validity of law.
Kelsen propounded the pure theory of law and separated law from society. He defined law as binding norms. He propounded that their is a higher norm "grundnorm" that is supreme and all the laws of the land take their validity from it.
According to this theory, legislation is the main source of law.
(3) Historical school: as per the historical school, law is the outcome of long historical development of the society. The historical school takes customs as the most important source of law.
Savigny propounded that law is the outcome of popular consciousness (volksgeist). Law evolves in an organic manner with the society.
(4) Sociological school: it focuses on the interaction of law and society and lays a greater emphasis on legal institutions. It states that law has source and sanction in the social needs and necessities.
Roscoe Pound stated his theory of social engineering, under which a law maker acts as a social engineer by attempting to solve problems in society using law as a tool.
Legal realism propounded by Justice Cardazo, Lewellyn, Justice Holmes states that law is like a putty in the hands of a judge who moulds it and gives it a desired shape based on his own biases and the facts of the case. American legal realism lays a greater importance on the role of judges as the law maker and interpreter and lays greater importance on precedence as the source of law.

Reservation in educational institutions and government jobs

While the Constitution of India provides for equality under Articles 14-18,  with Article 14 providing equality before law and equal protection of laws. Article 15 prohibits discrimination on the basis of religion, race, caste, sex or place of birth and Article 16 provides for equality in opportunity in matters of public employment. Article 17 abolishes untouchability and Article 18 abolishes titles. However, articles 15(4) and 16(4) talk about special provisions for the backward classes.
In the case of Champakam Dorairajan v State of Madras, the Supreme Court struck down the communal GO, which made reservations based on caste, leading to the first amendment of the Constitution.
Article 15(4) states that "nothing in this article or in clause 2 of article 29 shall prevent the State from making any special provision for the advancement of any socially or educationally backward classes of citizens or for the scheduled castes and the scheduled tribes"
Article 16(4) states that: "nothing in this article shall prevent the State from making any provision for the reservation in appointments or posts in favor of any backward class of citizens which, in the opinion of the State, is not adequately represented in the services under the State"
In the case of Balaji v State of Mysore, the Supreme Court observed that reservation cannot be greater than 50%. The classification between backward and more backward was held to be invalid. Further, it was observed that caste cannot be the only criteria for reservation as caste us not synonymous with class and other factors including economic backwardness should also be taken into consideration.
In Devdasan v Union of India, the Supreme Court held that the carry forward rule is unconstitutional.
In State of Kerala v NM Thomas, the Supreme Court held that a 2 year relaxation for SC/ST for passing a test for promotion was valid as they were ultimately required to pass the test.
In State of MP v Nivedita Jain, the Supreme Court held that the relaxation of qualifying marks for SC/ST for admission is valid.
In Indira Sawney v Union of India, the Supreme Court held that reservation cannot be more than 50%, the classification between backward class and more backward class is valid, carry forward rule is invalid. It further held that the creamy later should be excluded. It further held that reservation in promotion is invalid which was nullified by the 77th amendment.
The provision of reservation is not in contravention of the equality provisions but rather a means of providing social justice and bringing the backward classes at par with the forward classes.