Introduction:
The UPSC Law Optional Subject is an important subject for candidates aspiring to become civil servants. It covers various aspects of law and legal systems. One of the ways to prepare for this subject is by studying case studies that are frequently asked in the UPSC examination. These case studies help candidates understand the practical application of legal principles and concepts. While there are several case studies that can be asked in the UPSC Law Optional Subject, let us discuss a few important ones in detail.

Case Study 1: Kesavananda Bharati vs State of Kerala (1973):
- This case is one of the most important cases in Indian constitutional law.
- It deals with the doctrine of basic structure and the power of Parliament to amend the Constitution.
- The court held that the Parliament has the power to amend the Constitution but it cannot alter its basic structure.
- This case established the principle of judicial review and the supremacy of the Constitution.

Case Study 2: Maneka Gandhi vs Union of India (1978):
- This case dealt with the issue of the right to travel abroad.
- The court held that the right to travel abroad is a fundamental right under Article 21 of the Constitution.
- This case expanded the scope of Article 21 and introduced the concept of procedural due process.

Case Study 3: Bachan Singh vs State of Punjab (1980):
- This case dealt with the issue of the constitutionality of the death penalty.
- The court held that the death penalty is constitutional but it should be imposed only in the rarest of rare cases.
- This case laid down guidelines for the imposition of the death penalty and introduced the concept of balancing aggravating and mitigating circumstances.

Case Study 4: Vishaka vs State of Rajasthan (1997):
- This case dealt with the issue of sexual harassment at the workplace.
- The court held that sexual harassment violates a woman's fundamental right to equality and dignity.
- This case laid down guidelines to prevent and redress sexual harassment at the workplace and introduced the concept of Vishaka guidelines.

Conclusion:
These are just a few examples of case studies that are frequently asked in the UPSC Law Optional Subject. Candidates should thoroughly study these cases and understand the legal principles and concepts involved. By doing so, they will be better prepared to answer questions related to these case studies in the UPSC examination.