Keshavananda Bharti case:
The Keshavananda Bharti case is a landmark judgment delivered by the Supreme Court of India in 1973. It is considered one of the most important cases in Indian constitutional law as it determined the scope and extent of the amending power of the Parliament and the basic structure of the Constitution.

Background:
The case originated from a constitutional challenge to the Kerala Land Reforms Act, 1963, which sought to impose restrictions on the right to hold and transfer land. Swami Kesavananda Bharati, the head of a religious institution, argued that the Act violated his fundamental rights. The case was heard by a bench of 13 judges, the largest ever assembled by the Supreme Court.

Key arguments:
1. The main contention in the case was whether the Parliament's power to amend the Constitution under Article 368 was absolute or subject to certain limitations.
2. The petitioner argued that the Parliament's amending power did not extend to altering the basic structure of the Constitution.
3. The government, on the other hand, asserted that the Parliament had unlimited power to amend the Constitution and that no part of it was beyond its reach.

Judgment:
The Supreme Court, in a historic 7-6 decision, held that while the Parliament had the power to amend the Constitution, it could not alter its basic structure. The court ruled that certain essential features of the Constitution, such as the supremacy of the Constitution, federalism, separation of powers, and the independence of the judiciary, were part of its basic structure and could not be amended.

Impact:
The Keshavananda Bharti case established the concept of the basic structure doctrine, which acts as a limitation on the Parliament's amending power. It ensures that the core principles of the Constitution remain inviolable and protects the fundamental rights of the citizens.
The case also had a significant impact on subsequent judgments and constitutional amendments. It led to the development of various principles, such as the principle of harmonious construction and the principle of prospective overruling.

Conclusion:
In conclusion, the Keshavananda Bharti case is a landmark judgment that defined the limitations on the Parliament's amending power and established the concept of the basic structure doctrine. It has played a crucial role in safeguarding the fundamental principles of the Indian Constitution and upholding the rights of the citizens.