What are the disadvantages of Public Interest Litigation?

The disadvantages of public interest litigation are as follows:

• There is always the possibility that the instrument of PIL may be misused by a person purportedly litigating in the public interest.
• The popularity of PIL, has resulted in a large number of such cases being filed, which add to the already considerable backlog and which also require the court to spend a lot of time in dealing with issues that should more appropriately be dealt with by the executive or the legislature. 
• Besides, considering the nature of the cases involved, the orders of the court are not easily enforceable, thereby requiring the petitioners to approach the court again for subsequent direction. 

Further Reading:

• Public Interest Litigation (PIL) in India
• Indian Polity Notes